I can remember getting a negative HPT and being over a week late so went to my GP and told him that we were TTC, was late and had a negative HPT. He sent me straight for a BT with it marked *urgent* so I could get my results the same day. But they were negative.
The second time I went - similar thing except AF wasn't late and I got a positive! So I think it largely depends on your dr and your relationship with them. My GP knows I'm a nurse and it has to be important for me to go to the Dr so respects me a little more for that (straight from the horses mouth).
Good luck and hope you get the right result

MG