Most likely you're safe. Just want to let you know... for future knowledge: Just because you pull out before you climax doesn't mean you're safe. Condoms make you safe, or at least a LOT safer. Men sometimes expel a small amount of semen long before climax and they don't even feel it. This semen is just as sperm filled as the rest... and it only takes one swimmer. Also, you may want to talk to your girlfriend about her "monthly cycle". It's a weird conversation to start, I know, but women that keep track of their period can then also know when their least likely... and MOST likely to get pregnant. If she, or you, or both of you know she's ovulating, then you can take that extra precaution and avoid sex all together for a few days. Good for you in being responsible and keep it safe!