Parents concerns

My parents think I am forming a eating disorder because I don't like to eat a lot. The reason being is that I get really nauseous everytime I eat. I try to explain it to them and they won't believe me. I think I might just have acid reflex or something of that nature. I am a teenage girl and have always had body image problems. I don't think I have a disorder though. I don't know how to explain to my parents that I am fine. They are now practically forcing me to eat when I really just don't want to and I get sick everytime. What do you think it could be?