Fertile window was the 8th to the 12th, had sex at 2 am on the 13th. took plan b to be safe. chance of pregnancy?

Fertile Window?: If she took Plan B in the right time frame, then there should be no pregnancy. In my opinion "fertile windows" are not that reliable. Unprotected sex in a fertile woman can lead to pregnancy.

Any time: any time you have sex no matter if you use a condom, on birth control or even plan B, there is always a chance of pregnancy.