So Far I'm 11 Days Late. I'm Having Pain By

So far I'm 11 days late. I'm having pain by my left rib which usually is a sign that I'm backed up. I got a negative result for my pregnancy test at my GYN. I informed him that I had pain around my pelvis area but he didn't comment on that. I've been reading about pregnancy tests changing from negative to positive after a few weeks which kind of scares me. Any help?