If you are using both condoms and birth control then it is highly unlikely that she is pregnant. Though the only 100% sure way not to get pregnant is by not having sex, still your chances are very low.
Being late is not that big of a deal. Women are not always right on time every single month. She might have miss counted or got the last date wrong. Even so women who have been like clockwork can still have "off" months.
If it is a concern, just go to the store and buy a home pregnancy test, though waiting a few more days wouldn't hurt.
