Pregnancy testa failed but still pregnant?

I have read soo many stories about people who not only failed at home pregnancy test but bloodwork came back negative too! Pregnancy was finally confirmed by ultrasound! Has this hapened to you? I took 2 test one yesterday and one today and they came back negative, i am 8 weeks late on sat could i have skipped a period and then become pregnant its 5 days before my next should be here (going by my normal 32 day cycle) that gives me a 51% chance of accuracy using clear blue digital... i need some encouragment.. my are so sore, i ave nausea, light stomach cramps, bloated stomach, bumps around areolas, people are asking me if i am pegnant! (i guess im probably just fat (135lbs though) ) I have not gotten a blood test yet