Is it possible for a blood pregnancy test to be wrong? My period is 6 weeks and 1 day late, I've taken three home test all came back negative went to the doctor this past Tuesday and did blood pregnancy test and checked my thyroid. The pregnancy test came back negative and my thyroid came back fine. A week before last I was having nausea, headaches and some hot flashes. I really felt like I was pregnant but then the blood test came back negative, but I've still not started. Please help. Thanks