I have never had anorexia, only mild bulimia, but my best friend was hospitalised with anorexia so I know a fair bit about it... So I will try my best to give you good advice.
I think the best thing to do in your case would be to talk to somebody... Whether it be a parent, teacher or your doctor.
Do you not eat so that you lose weight or is it purely because you feel sick after eating?
I really think you should/hope you talk to somebody incase this is an eating disorder and is getting out of control. the earlier you can recieve help the better.
Hope I helped a tiny bit x