L.A.
I am *so* sorry for your stress. I can only imagine how difficult it is.
For two year olds, if they aren't growing, their daily calorie needs are quite small. My uncle used to joke that two year olds lived on air.
To help ease your stress, why not start a food diary? She probably isn't eating well at all meals, but over say a week's time, she has gotten a better balance. Perhaps one day more fruits and another more grains and another not so much of anything. Looking at all of this over time instead of a single day gives a much better picture of her diet.
Lastly, have you tried liquid nutrition? For example smoothies. you can put all kinds of stuff in there - yogurt, flax, tofu, peanut butter.... If you search for nutritional kids smoothies or drinks, some really good ideas should be really easy to find.
good luck! Ad hopefully your OT will have some good ideas for you as well.