Most companies that manufacture oral contraceptives give a minimum of seven days of active pill taking before the female can consider herself protected, and therefore have unprotected sex. If your girlfriend has been on them longer and has been taking them regularly, not missing days, etc, than you should be fine.
Copyright 1998, 2014 Heather Corinna/Scarleteen
Scarleteen.com: Providing comprehensive sex education online to teens and young adults worldwide since 1998
Information on this site is provided for educational purposes. It is not meant to and cannot substitute for advice or care provided by an in-person medical professional. The information contained herein is not meant to be used to diagnose or treat a health problem or disease, or for prescribing any medication. You should always consult your own healthcare provider if you have a health problem or medical condition.