i'm 16 and had sex with my boyfriend.. HELP!!!

i'm 16 and i'm on birth control and my boyfriend and i decided to have sex. except we decided to have a sex a week before my period. we had sex on friday and again on saturday then again on monday. my period hasn't started yet and i've taken to pregnancy test and they both said i wasn't pregnant. the thing is my new birth control pack starts tomorrow and i still haven't started. I need help!!!!!!