I'm much the same way - I used to eat very little not because of any sort of ED or body image issues, but because I felt full and sick too quickly. I was getting maybe 1000 a day, and thought there was no way I would be able to fit in 2500-3000. But I still got there, by going in small increments and seeking out higher-calorie foods. Drinking whole milk instead of soda or water, getting lots of high-cal foods like granola and peanut butter, just going up a few hundred every week. Now I'm able to eat larger meals, I get hungry faster, I find myself going back for more...it just takes patience and dedication.
This is quite normal in the beginning. I told myself there was no way I would ever make 2500, but now I could actually eat more. There were days when I was so full, but I fought through it. Your body will readjust eventually. If you're not that hungry try starting out with more liquid calories, whole milk, milk shakes, juice, smoothies, etc. Like jbryan said, also things like nuts and peanut butter help a lot. When I began recovery from AN, I increased 250-300 every few days, but some people do it faster than that. Just do what works for you and makes you the most comfortable.
i have been slowly recovering for the past 4 months, i was able to speed up my metabolism but that wasnt enough. i was maintaining my weight at eating about 2800 a day. i have bumped it up to about 3300+ calories in a week and i am having some issues with it. i feel so full all the time, i never have that light feeling in my stomach any more. but its getting better and its only been 6 days. i the body gets used to the increase in calories even if you dont do it gradually. its just hard for it. i always have a food baby (my stomach has been protruding as i am full all the time) but i think thats starting to go away. i herd after about two weeks the body gets more used to it. i have gained about 4 pounds but i dont know how much actuall body weight that is as my body fat % is still only 5% so i am going threw the same thing but its a bit different from me since i didnt just start my recovery 6 days ago, i only just drastically changed my eating six days ago.