I think that it's clear that if you're only getting 1000 calories per day, you need to find some way of ensuring that you get enough (more!) to eat. Whether that's by counting calories (fitday.com is great) or by counting servings (like the vegetarian food pyramid) you definitely need more calories.
By the way, according to what you wrote, you have a BMI of a little under 18 (healthy range is 20-25). You may actually want to eat more than you need to maintain your weight to get up to a healthy weight. (For example, add 500 to the 1600 calories you need to gain 1 lb per week).