I don't know why your dr. wouldn't give you a blood pregnancy test while you were in. It would be accurate if you've missed 2 AFs. My dr. accepts any positive as a positive. My only advice is to try another brand and make sure (like quadruple check) that you follow the directions to a T since they can vary HPT to HPT and everything from how long you pee on the stick to how long you wait to read the test can influence whether or not you get an accurate answer.
Sorry I'm not more help! GL!
Rae (27), DH (26), Lucas (6/3/12), #2 due in December