ME and my girlfriend had sex on the day that she first got her period, we have used a condom every time since the last period, but after we had sex the day she got it, the next morning she woke up with no period, what could the reasons be of this, she still has her period symptoms, such as swollen breasts, cravings for salt, it almost seems as it should start later this week, but her period never seems regular to me, PLEASE HELP US :-(