Missing Period!

I started birth control 2 months ago (starting the 3rd pack today) I take it every morning diligently (I have an alarm set so it's the same time every morning) and when I have sex I always make sure he has a condom and he always pulls out before he comes. I haven't gotten my period yet, is this a sign of the birth control, I slightly remember my doctor saying that if takes a few months before it works out but I just want to confirm with others that it's just a side effect of the birth control