Hi, i'm 18 and am infrequently sexually active. I haven't had my period in 7 months which worries me but i'm clearly not 7 months pregnant. The last time I was sexually active was a month ago and I am absolutely positive I'm not pregnant (I would have been able to tell by now) but all my doctor did was try to take a pregnancy test, which I refused. Any other ideas about why I haven't been getting my period? I'm on birth control and am a vegetarian.