Just know that birth control pills are not 100% effective against pregnancy. So a back is always reconmended. However, if you have not been using a back-up then I would say you are in the clear from the antiboitics.
Usually antibiotics only interfere with your birth control for as long as they're in your system, so I would say yes you're probably in the clear now. However, I would call my pharmacist and ask just to be sure :).