Completely Lost

My wife and I inseminated on Christmas eve. In January I had a period (or I bled). This month I am 12 days late which is extremely unusual. I have NEVER been more than 2 days late at most. Blood work and pregnancy tests both say negative. I’ve had nauseous in the morning for four days, almost threw up eating a banana which I ate daily.

At this point, I would be 8 week but again, the tests said negative. I have an ultrasound scheduled for next week.

HAS anyone known someone who had negative tests and were still pregnant?