My Girlfriend can't go on the pill and won't have sex with me cause she is...

[BedroomSpice]

...paranoid of getting pregnant? What can I do to help her come to terms and give her some piece of mind?? I have told her that I will wear a condom and everything. She says she is ready and really wants to but can't get over the fact that she might get pregnant. We are both ready to go the next step but her mind just goes crazy and she over thinks some things. Can Anyone Help Us????