PCOS and pregnant?

TJ
LMP was 15 November. My abdomen is severely distended but with no pain. Just darker skin around labia, slightly more prominent veins in breasts along with slight fatigue and occasional slight nausea. I have severe PCOS (loads of cysts, but not overweight or with many other symptoms besides irregular periods) and I only chart periods. I've taken two tests, one Friday afternoon and one Saturday Morning (both BFN), but I wouldn't think I'd be 4 weeks pregnant and it could cause this amount of distension. Had two 29 day cycles in a row, and would have been due if that held this month. Called my surgery and its three weeks for an appointment. Any advice? I'm starting to freak out a bit. I can't even fit in my normal trousers. Looking at the photo, I'm normally almost completely flat stomached. HELP!