I keep taking pregnancy tests and they keep coming out negitive. I went to the Gyno and they took blood to check my thyroid levels as that I have under active thyroids. However I do take medication... they also took blood for pregnancy and I think that will come out negitive. I had to push my AF back, the first day should have been on the 9th. I have never had late AFs. What is they latest AF you have had and not been pregnant.