Dee - i got BFP's on HPT's for four days before my BT - and when i had BT, my HCG was at 26 - as a rule, anything under 25 is considered "not pregnant" - so it's possible that your HCG is simply too low for BT to confirm pregnancy, but you have a sensitive HPT that is registering it nicely

i would be asking for another beta tomorrow from a different doctor - ask for a quantitative (with the hcg number) not just a qualitative (yes or no result). it sounds like the doctor today needed a personality transplant!!