Hi there.
You need some accurate information. First, what you precum is actually Cowper's Gland secretion. This happy little gland secretes a milky fluid prior to ejaculation. It MAY contain millions of sperm left over from a previous ejaculation. thus, coming into contact with your girlfriend's vagina, even without having an orgasm, can result in pregnancy. It's statistically unlikely, but not impossible.
So, use a condom if you're anywhere near her vagina, OK? If you’re worried about pregnancy, she can use emergency contraception (Plan B) within 72 hours. This is available at your local pharmacy. For more information, call the Emergency Contraception Hotline at 888.NOT.2.LATE/-668.2.5283. If it's after 72 hours, your next step is to use a home pregnancy kit for a preliminary determination of whether she's pregnant. Buy one that says it can be used within 4-5 days of unprotected sex. If it’s positive, she should make an appointment at her school clinic or the local women’s clinic.
Condoms are widely available in every drugstore, as are contraceptive gels and creams. And there are many other forms of birth control that are available without a prescription as well. I urge the two of you to go online to the following site and read everything about risk reduction. This is a great site with lots of good information:
www.scarleteen.com
In addition the MedHelp safe sex site also has lots of good information:
http://www.medhelp.org/medical-information/show/1723/Safe-sex-
Remember that with great sex comes great responsibility, so find a form of risk reduction that works for you. Play hot, and play safe. Best of luck to you. Dr. J