I've had my period since I was in the 5th grade. I'm 35 now. I have a child that is 9 months old and I've had my period back for 6 months. It's been regular with no problems. I had unprotected sex on the 11th which was less than a week before my period and now I've had a missed period. I've taken three first response early detection tests and they were negative however it hasn't been that long since we had sex. I wasn't worried about anything so I don't feel that has caused the missed period. I do have cramping but I still haven't started. It's been 37 days since my last period. Any ideas as to what I should do? Could there be another reason? I don't think I was ovulating but stranger things have happened. Any help would be greatly appreciated.