My boyfriend and I had an unprotected sex. He didn't use any condom and I am not taking any birth control pills. This happened today; four days before my menstrual period. It's my very first time to experience that someone cum inside me. I don't know what to do and what to feel. I'm so afraid to get pregnant. I don't want to get pregnant yet. I know it was a huge mistake to have sex without any protection. But please help me, how can I prevent pregnancy? And what are the things I should do for me to not get pregnant?