Hi Fah_Sostenido and welcome!
Before I share anything, I wanted to mention that there is a thread here in the "Diets and Losing Weight" forum for those with eating disorders of any type to share their experience and seek or offer support. If nothing else, just reading through that thread might give you some insight and help.
I am only speaking from experience as someone who has suffered with en eating disorder for many years, starting as an omnivore in 2006. I went through anorexia nervosa, and periods of bingeing/purging, recovery and regaining weight, relapses and everything in between. I am currently EdNOS (low normal weight but still struggle in some mild ways with the mental aspects and with some exercise addiction). I also tried various eating disorder treatments (some forced, some voluntary), overeaters anonymous (even though I was very underweight at that time, I was in the throes of bingeing/purging), and as a vegan I tried different styles of eating like all raw, or Eat To Live and so on. None of those worked because 1. I did not need to lose weight and 2. They served to create yet more restriction and obsession with food.
Its' difficult to know where you are coming from because we don't know anything about you...your weight, health problems, history, what and how much you eat on a given day, activity level, other mental illness, life experience. It's never really as easy as following a diet plan is it? When I read your post over and over, I get the sense that this isn't so much about your relationship with food as it is your relationship with your body and yourself. I think that is something beyond the scope of what strangers on a forum can help you with. But I can certainly relate to that anxiety, the fear of weight gain, wanting to have some sense of control over your body and maybe your life. Food is always the easiest and first weapon people turn to for that. It holds a promise or a curse. Avoid this and lose weight. Eat that and you'll gain. So much of what we learn about food is cultural, or media based and not so much on science or practicality.
I support what David3 said in his post before mine. If you want to eat a plant based vegan diet, it's best to focus on the basics such as the vegan food chart as shown above. When I first went vegan, I had a lot of worries as far as meeting various needs (calcium, protein, zinc, DHA to name a few). I discovered a book called "Becoming Vegan: The Complete Guide to Adopting a Plant Based Diet" by Brenda Davis, R.D. I LOVE this book because she goes into comprehensive detail about meeting basic nutritional needs without steering one towards any particular style (ie starch, raw, etc). She uses double blind studies as references to back up her information, and speaks in practical terms. There are also chapters specific to athletes, elderly, pregnant women, those trying to lose weight and those suffering from eating disorders. I would highly recommend this book. I have recently seen it at my local library and I ordered mine through Amazon.com. She does not push any particular agenda beyond eating as a vegan, other than to eat reasonably healthy. I like that she is a professional registered dietitian too.
Everyone is different, but what has helped me is eating four small meals a day at regular intervals so that I am never too hungry and so that my metabolism keeps working efficiently (I am not trying to lose or gain weight at this time, just trying to maintain and eat well). Large meals are triggering to me, though I can handle them here and there. When I was in a weight gain/recovery mode and also in most treatment programs, they have you eat six meals and snacks each day, even for those trying to lose weight, so that your body can regain it's metabolism and heal from years of restricting, and also gain an understanding and sense of normal hunger cues. Restricting leads to hormonal imbalances, including appetite hormones like leptin and gherlin, which are triggered and increase in response to eating too little or exercising hard while not eating enough. It is not uncommon for those who have restricted for a long time to go through periods of bingeing, which can be a response to increased appetite hormones. And of course, the types of foods we binge on tend to be those "forbidden" or easily attainable foods that require little preparation and are laden with fat/sugar, because that is what our mind and bodies are screaming for. Bingeing also encourages insulin imbalances and dysfunction, and promotes fat storage. Dieting encourages a merry-go-round of restriction, weight loss, hormone imbalance, deprivation, reactive and physical bingeing, more weight gain, and repeat cycle. The more one focuses on food and dieting, the more power food has over a person. Going back to basics, learning what your body needs to be healthy, learning how to enjoy food again without going from one extreme to the other (all processed all the time versus only fruits and vegetables etc), finding balance is key to recovery. But even more so is just accepting your body and loving it no matter what. This is one of the hardest things to do in a world that teaches us to hate our bodies, especially women. I could write a dissertation about that, and it is an ongoing struggle I battle daily, though I have come a long way in my recovery.
It has taken me a long time to become more flexible with my eating and allow for processed foods here and there while still largely enjoying whole plant foods every day. I try to focus on eating to fuel my body through all kinds of exercising that I enjoy...cycling, dancing, canoeing. But I also understand that food is more than simply fuel. Food can be enjoyed, and celebrated, and it can make you feel good. No need to feel ashamed of any particular plant food you eat. But I understand that mind set. For years I avoided fats as I feared those the most due to all the bad press and because they are more calorific. But not all fats are created equal, and some fat is essential for absorbing important nutrients such as fat soluble vitamins (D, A, E). I can eat a small handful of almonds in a day, or a few teaspoons of coconut oil in a stir fry and it isn't going to cause me to gain weight or drop dead from a heart attack. Allowing a few of these kinds of foods each day lessens the power they hold over me. When they are not forbidden, they are no longer this thing I crave. Whole grains help me feel full and warm inside and give me sustained energy. Do you ever eat brown rice, quinoa, Bulgar wheat, barley, oats, couscous? They are not only a source of fiber but protein, b vitamins, even some vitamin E and they keep blood sugar stable. Nuts and seeds provide a great source of magnesium, vitamin E, omega 3 fatty acids. Beans are great for protein, fiber, iron, even some calcium. Fruits supply ready energy and are sweet and enjoyable and provide water too. Vegetables are great for fiber and micronutrients. Even potatoes can supply potassium, vitamin C, and provide satiety. You don't have to eat JUST potatoes at a meal. How about some steamed or roasted broccoli and black beans with it (which can help keep blood sugar from rising and crashing versus a potato by itself)? and a nice vegan sauce? I sometimes incorporate some processed vegan foods like Just Mayo or Daiya shreds as long as the majority of the meal or snack is healthy and whole. It keeps me from feeling deprived and too strict, but is not something I rely on for every meal. It's a treat, something different once in a while. In fact, I had some recent extensive lab work done due to concerns about iron (I have bruises that are taking a long time to heal). My iron ferritin and hemoglobin were actually perfect, as well as most labs, but surprisingly (or not so), my glucose and sodium were rock bottom normal, close to too low. This is probably a good sign I am 1. not eating enough for my body to recover after strenuous exercise and 2. too strict with sugar and salt intake. It probably explains the leg cramps I have been trying to ignore, and is a valuable lesson in listening to your body, though I know this can be a challenge sometimes too.
If this is really just about changing your lifestyle to be healthier, even small changes can make a big difference. Finding some form of exercise you enjoy (such as a brisk morning walk or yoga etc), getting enough sleep, adding a few more whole grains or beans etc in each day and seeing how it makes your body feel. Positive affirmations to yourself. But to me it seems like this is something much bigger than lifestyle that you are dealing with. I would encourage you to find a therapist or dietitian to talk to, or even your doctor. I started with my doctor years ago when I was having a lot of anxiety around food and body weight and obsessive/irrational thoughts. Weighing after every meal is a sure sign that this is more than making lifestyle changes. And BTW, it is VERY normal for weight to fluctuate by three to five lbs (or a few kgs) a day. it would be more abnormal for weight to stay exactly the same all the time.
I've probably rambled way more than helped lol, but I hope you can find the support you need to make this work! You CAN be healthy and happy as a vegan without constant vigilant restricting and dieting. But vegan isn't a license to eat everything and never gain weight. The key is balance, and discovering healthy and satisfying ways you CAN eat as a vegan without needing to go to extremes which can be very triggering for a person prone to disordered eating.
Best wishes and hope to hear more from you!