I had a condom on and then it fell off and I didn't know so I didn't pull out

First thing you should do is get her to take a pregnancy test. If she is pregnant, you are going to have to tell your parents. I know it will be hard. But they need to know about this. Also, don't abort. Instead, take her to see your local crisis pregnancy center. They have counselors there she can talk to about her options and they can help her to figure out what to do. Also, I would recommend looking up OptionLine. It's a group that helps people in these types of situations (they'll give you much better advice than I can.) If you call the number on their screen, they can help you figure out what to do (they also have a search engine for crisis pregnancy centers. It's under Find A Center Near Me at the way bottom of the page.)