Birth control pills have completely stopped my period, please help?

I've been on birth control pills for over a year and my period has completely stopped. My friend is on the same type of pill (Loestrin) and she still gets her period. I'm definitely not pregnant, so I'm really stressing that there's something wrong. Is it normal for birth control pills to completely stop you from getting your period and if so, if you go off them will your period come back? Just freaked out that I'm infertile or something...Thanks