Just another pregnancy question...?

no doctors hpts are no diff than the ones we buy...they all do the same thing-detect HCG, it is very possible that you ovulated late....I was in a similar situation I was a few days late and when I tested i got a neg then i tested again 4 days after that with a dollar tree test and got a faint positive that i even had to show ppl to decipher whether i was looking too hard or not....the next day i held my urine until i got to my dr office and got a + test....I also am on levothyroxine for my thyroid so I know what you mean about being regular....I had clear sticky CM on april 25th....but i didnt conceive until a week later soooo conception can surely happen later than we "calculate"