Not pregnant, no period. Is this normal?

Hi, my partner and I have unprotected sex. I have had tummy cramps for the past week on and off and am 5 days late for my period. I've taken a pregnancy test but, it was negative. I was wondering if anybody could give me some advice? I also had a miscarriage about 2 months ago. Would that have anything to do with me being late? Thanks to anyone that can help me :)