What's going on??

Ashley
So my period was due Thursday and still has not started. I have been off birth control since February and haven't missed or had a late period at all. We are recently married and not exactly trying to get pregnant but wouldn't be upset if we did. So we got back from our honeymoon a week ago today. I tested when we got back home and it was negative. Waited until today to test again since my period has not started and another negative.
No stress or anything in my life right now...so what the heck is going on?