I don’t have any experience with eating disorders but I do have experience with the feeling that I know I should eat more but being totally unable to eat another bite. What has worked well for me is drinking more calories. I feel like I’ve read time and again that our bodies don’t register calories the same way when they’re drank and that really has been my experience. I drink whole milk and chocolate milk throughout the day without it significantly impacting my appetite and that is boosting my overall calories by a MINIMUM of 1200 calories, sometimes over 2000 if I’ve had a thirsty day (this is JUST the milk, I do eat too) and I’ve seen the biggest leaps in my metabolism in the last month and a half since I started drinking lots of milk. I just hit 98.8 this morning!
I’ve seen a lot of references to Youreatopia as a great resource for recovery from eating disorders so I’ll second that you probably should take some time to check that out.