Christina,
I can't give you a statistical figure, but it is possible that you might be pregnant. It would probably be too early to take a test at this point though. Wait until you actually miss your period (or maybe even a week later if your are still late to take a pregnancy test). I understand your worry, but try to relax until you know that you are pregnant. Will your bf be supportive of you and the baby if the result is positive? I would stop having unportected sex if you both do not want to become pregnant. Good luck.
Kate