ive been on birth control since i was 14 and im now 17...my mom wanted me to get on it even tho i was a virgin because she jus wanted me 2 be on it in case i did have sex...ive never had a late period...but the other day i had sex for the first time the day before i should have had my period and then i had sex again the day i should have started my period and now i havent had a period yet. could having sex for the first time when ur on birth control cause u to have a late period? please help!!