I went to go visit my girlfriend for her birthday and we had sex while I was there. I pulled out before I was about to go, and didnt think much of it. I left 2 days later and my girlfriend had her period the after I left. But the thing is her period was a week early. She said that it was a normal period nothing different then her other ones except for the fact that she was early. I was really happy that she had her period but now she is a 1 1/2 weeks late for her next period and she thinks that she might be pregnant. I keep telling her that it is most likely stress bc she is finishing up her senior year of college, and has a million 20 page papers to write. Is this possble, and if so what are the chances of something like this happening? Some one please help bc I dont know what to tell her, and we are both starting to get really afraid.