I wish I had similar problems to you. I'm overweight. (Gotta love the wheelchair and the fact I love food)

Are you on any antidepressants or other drugs that may cause a decrease in hunger?

I'd recommend smoothies, whey powder, or slowly trying to up your food intake. Don't try all in one day, but adding a small snack for a week and then adding another one may expand your stomach so you'd be hungry again.