Do I have a disorder?

I barely eat, not because I don't want to but because I'm never hungry enough. I won't eat for a day or two then at random times I'll be really hungry and eat a lot and feel terrible about myself. I'm always told I'm getting too skinny and that I never eat enough but I can't help it. Whenever I try to eat and I'm not hungry, I just gag or end up secretly throwing out the food and saying I ate it. Is something wrong with me?