Can this be pregnancy or something else??

12 DPO, if I laying down and turn to the right I start getting pain like lower abdomen / pelvic pain and once I turn to the left I feel better, I just can't sort of lay on my belly without it making me uncomfortable or in pain.. I have this a long with other symptoms. I'm suppose to get my period in 5 days, I'm TTC. I never experienced this before. I took a test yesterday but it was a BFN.. Not only that but  I've been having on and off mild cramping since 6 or 7 DPO ... Can this be pregnancy symptoms or something else ??