I Had Unprotected Sex On March 2nd My Period Was

I had unprotected sex on March 2nd my period was due on the 4th..my periods usually start off with bad cramps and a heavy flow .for the last couple of days I've had cramps and a mild flow,not spitting because it's a dark red and it just mild,but usually it's heavy by this time.does that mean I can possibly be pregnant even though I was fertile a week and a half ago