Me & my boyfriend have sex every now & then & we always use condoms as our birth control . None of them have broke so far & im very thankful for that . The whole month of January I didn't get a period , then it came February & now it's March & im a week late . I don't know what to do , I've had sex a lot lately & was wondering if having sex too much can cause a late period . & I also I've been stressed just a little . I took a test Thursday or Friday & it was negative . Can anyone tell me what this may be ?