Depending on the timing, might have been a very early m/c. I had a test or two that was pos. when I took it at home, but a few days later my levels had dropped enough it was neg, or was at least low enough he had me retest in 24 hours to see if the levels were dropping (they were).
I really don't know why this happens, but after 6 1/2 years of IF and being on support boards, I have heard of it happening. It could also be a faulty test. One IF gal I knew, in a moment of goofyness, had her dh pee on the thing and it was positive.
Sorry about the negative. In your mind, if not your body, you were pregnant and the loss is difficult. I am so sorry.
Mom to 10yo Autistic Wonder Boy and 6yo Inquisitive Fireball Girl . December birthdays.