I had unprotected sex on the week I had ovulation and the day Id most likely get pregnant was the day I had the unprotected sex. Two weeks later I was due for my period.. And I got it today, so it was on time. But its different. This time my period is heavy and I have bad lower back pains and I NEVER, EVER have back pains. Could I be pregnant?

Most likely no, a heavy period is not a sign of pregnancy, a very light period or no period would be.