Could I end up pregnant?!

So me an my SO don't want any babies right now but we do have lots of unprotected sex. The other night we had sex on the last day of my period an he came inside me, an I know for a majority of women you can't get pregnant unless you ovulate. I have been watching my ovulation. An I'm due to ovulate in about 4 days. An sperm can live up to 72hours possible longer in the vagina. So my question is could I end up pregnant?!