17yr old girl on birth control pill hasn't gotten period since november. two otc pregnancy tests negative. otherwise healthy.

On BCP but no period: With 2 negative tests - doubt you are pregnant - first off if you are taking the pills correctly - they are very effective in preventing pregnancy. If there is any doubt - you need a blood pregnancy test done. If that is negative - the pills may be changing the lining of the uterus causing no menses. Best thing is to talk with the prescriber about this