I haven't eaten meat in almost a month now, and so far I've surprisingly maintained my weight, which was a concern for me as I was already underweight before cutting out meat. It seems like I'm eating all the time, really filling stuff that burns off in, like, two hours.

So, is it possible to gain weight if I double portions or something? My daily menu is something like this:
Breakfast: one bowl of cream of buckwheat or oatmeal, with nuts and fruit and a few baby carrots and one glass of chocolate soymilk. Sometimes a handful of pumpkin seeds.
Snack: usually two rice crackers with peanut butter or olive oil on top, and some type of fruit.
Lunch: rice pasta with some type of beans and veggies and a side of fruit or raisins sprinkled on top. Sometimes a rice wrap with pretty much the same ingredients.
Dinner: almost always leftovers from lunch, but I usually change the fruit and add a salad.
I have to say, looking at this list printed out, it doesn't seem like a lot

I really just want to gain weight without going back to meat. Please give me your opinions and suggestions.
Thanks!