I'm scared.

My fiancé and I had unprotected sex almost two weeks ago. I was due to start my period three days ago. I've been having cramps since Tuesday (it is now almost Friday), but no period. The cramps feel strange, not normal period cramps. They range all over from pubic bone to abdomen. They come and go. They are annoying but not excruciating. 
​Sure, I'm somewhat worried about pregnancy. But that would be okay. We are adults and we're getting married. What I'm worried about is if I'm NOT pregnant... Then what could be wrong with me? I'm 37, and have always had regular periods. But my last one lasted for nine days. Im really scared but I don't know if this justifies calling my doctor. Thoughts?