Hey , Before I had sex My period was perfectly fine! It was very regular , Now that I had sex , It haven't came on. I went to the obgyn, and they said that I was not pregnant and plus i got pap smear and checks for infections or stds . It all came out negative . I wasn't pregnant and i didn't have no infections or stds . So I have sex during the month of june , That's last time I had sex . I have sex the day of June4th and june 20th . That's the last time . I don't understand why my period haven't came on yet . I've birth control , could that possibly help?