Could I be pregnant?

Last month I had unprotected sex with my boyfriend on the day that my calendar says I ovulate. He didn't finish inside of me but we continued right after. So two weeks before my period I started cramping. I was a day late but my period wasn't normal it was lighter than usual and even after my period I was still cramping. I've been feeling really tired, my breast feel a bit sore, I'm cramping on and off. Could I be pregnant?