My boyfriend and I engaged in anal three days before my period was due. There is a slight possibility that he missed and went in my vagina. If he did, he only got one or two inches in and did not ejaculate. However, I have been cramping for the past few days which is normal for me before my period, but now my period is five days late. I'm fairly regular. Never off by more than two days.

I have been under a lot of stress from work this week and now this. I have taken a pregnancy test and it came back negative. Why am I late? Is it possible to miss your period completely one month and have it the next?