Food issues

I have zero appetite. Even when I'm so hungry I'm physically in pain I just don't want to eat and when I attempt to I get really nauseous. I try to eat throughout the day but usually I end up just eating dinner, if I eat anything at all. This has been going on for maybe two ish years and I'm not sure what it is or what to do. I cant go to the doctors, my parents won't let me because "not being hungry isn't a health concern" (I'm 16 and don't have a way to get there or pay for an appointment so its not in my control) but I cant just force myself to eat. I get really bad headaches all the time from not eating which is pretty rough when you put my anemia on top of that. Im not anorexic or anything like that, im actually a little chubby which makes even less sense to me. Does anyone have any advice as to what's going on and how I can stop it?