Pregnant w/o a BFP? Anyone?

Erica
Wondering if anyone out there has confirmed a pregnancy with a blood test w/o getting a positive urine test.
Today marks my period being 9 days late. I've taken a handful of tests and saw a very very faint positive on the first one I took (at 2 days late) but nothing since then.
My period has always been very regular, never more than 2 days late. I haven't experienced any of my usual pre-period symptoms.
I talked to my doctor and she said that if I get to the 2 week mark with no period and no BFP she will have me come in and do a blood test.