2 days late and a BFN but no AF

Yea... so I am two days late. My cycle is extremely predictable. Normally I can pinpoint the time of day my period will start. This cycle was no different I know I ovulated on Oct 26 which would put my start date on Nov 9. I have no normal PMS symptoms or anything. I took a test to see if I was pregnant and it was a very clear negative.

How many of you have had a false negative test? How long should I wait before either taking another test or contacting my dr?