Your friend is indeed misinformed, but it sounds as though she might have been taught abstinence-only education. As for you, it's a personal choice to have sex and one that shouldn't be taken lightly. If you make that choice, use protection in the form of condoms (because the pill does .N.O.T protect against sexually-transmitted diseases) and be sure you feel emotionally prepared for the experience.
If you are on a reliable form of birth control (like the .Pill, .Patch, or an .Iud and take it correctly, your chances of pregnancy are very low. Combined with the use of condoms, your chances of pregnancy are nearly impossible. Certain things do reduce the effectiveness of birth control pills, like antibiotics, st. John's wort, and some anti-seizure medications. Discuss methods of birth control and their effectiveness with your doctor if you have any questions, as he/she can provide reliable information.