The only testing my doctor would do is his in house pregnancy test, ofcourse came up negative. i do not have insurance and he refused to do any other testing. I have always been on time with my period maybe a day late once in a while but never 11 days late. I tried planned parent hood but when i spoke to the lady on the phone they do no do blood testing.
Did your doctor do any testing at all? If not, look for a different doctor (or call your own back) and tell him you want to have a beta blood test done. This will give you an answer one way or another if you're pregnant or not, and then you will be able to go from there.
Pregnancy isn't the only thing that can cause you to skip a month or be late, but it should be ruled out first before anything else is assumed.