My girlfriend and I had sex on December 29, 2016. We were both virgins at the time, so it was our first time, and we were both scared to get her pregnant, so we did anal sex instead. We didn't have any condoms at the time, so we ended quickly, about 5-10 minutes. I did not ejaculate, but I did notice some wet stuff around her anus. Maybe it was my pre-*** or the moisture inside her rectum. Please keep in mind that I do not masturbate, and I urinated a few hours before having sex with her. Anyway, her last period was on December 10, 2016, 20 days before our intercourse. She doesn't track her periods though, but if we follow the regular cycle, she should have hers by January 6, 2017. A few days after sex, she started having symptoms like a bigger lower abdomen, nausea for a single morning only (maybe stress), and migraine for a single evening only (again, maybe stress). She says she has these symptoms before periods as well. Now it's January 8, two days after her expected period, but she still hasn't had hers yet. She has been very worried and stressed for the past few days, because she thinks she might be pregnant. We can't have a pregnancy test, because our parents would kill us. Now, she doesn't have any symptoms anymore, and her abdomen has returned back to normal. What is the chance that she is pregnant? Is it normal for stress about thinking you are pregnant to delay your periods? We will certainly cease to do stuff like this anymore.