too soon to test?

the first day on my last period was 02/12/08. i took a home pregnancy test on the 10th that was negative, and had an hcg test at the doctor on the 12th which also came back negative. my doctor told me if i dont get my period in the next few days to test again because it could still be too early.

i am now two days late. i want to take a test in the am tomorrow. is there any chance that the hcg test was just done too early and that's why it was a BFN? would it have something to do with Feb being such a short month that my period would actually come a little later than expected?