Underdeveloped breats?

I'm 17 and got my period when I was 13, but my have stayed the same. Their not round. My mom says that I just haven't filled out yet.. But its making me depressed. All my friends have round and full s and i'm stuck with these.. Mutants. I have Endometriosis, and to treat it I have to go on Birth Control. So I was wondering, with the added hormones, will this make my fill out?