Help!

Ok....so i had my period about two weeks ago and i had sex with my boyfriend like days after it ended. We did thw withdrawal method and even after i took a morning after pill. Its two weeks later and my period is here again.... i'm aa little scared and worried cuz i dunno why. And thee scary part is same thing happened last month. I was worried i might be taking the pills too much. They've messed with my cycle before but this one is different....is it just the pill or should i be worried?