Alright so me and my girl friend had sex a couple months ago and we were worried that she was gonna be pregnant, but she ended up having her period about a month ago. However, today she told me that she's late on her period and now i'm worried that she may have mistaken last month's period for implantation bleeding. When we had sex, i didn't actually ejaculate inside of her and the only thing that may have come out is pre-cum. Lately, she's been doing alot of exercise due to an athletic program for our school and she's also been quite stressed since our relationship has been rocky lately. I've heard that exercise and being over stressed can make a period late, but i am still quite worried. My girlfriend told me that her period last month was like every other period she's ever had, but the fact that this month's period is late gets me thinking.. we haven't had sex since the last scare we had, so I don't know what's happening. Any information is helpful. Thank you %-)