What Causes Abdominal Pulsations And A Missed Period?

Hi, I had my last period 31 days ago. I believe I had unprotected sex during ovulation. I believe i was ovulating because i had LL abd pains for 2 days the same day I had unprotected sex. It was day 18. Yesterday my period was due to start. I took 2 cheap walgreens pregnancy tests and they were both positive but the positive confirmation strip was extrememly pale. That was yesterday. Today ive been having gentle pulsating abdominal pulsations all day. What do these phlsations mean? Could i be misscarrying?