My boyfriend and I were fooling around about two months ago. He was inside me for a very short time only once or twice, and I shortly rubbed his penis on my vagina too. I got my period on time the next month, but it only lasted 5 days when it usually lasts 6-8. For a little bit, it was darker than usual too. This month, I still haven't gotten my period, its 3 days late. The only pre-period symptoms I have is sore breasts. Could I be pregnant?