Pregnancy Help!

Okay ladies, so I am on birth control and have an alarm set to remind me to take it at 10 every night. However, I typically take it between 10-12. My boyfriend and I normally use a condom even though i'm on bc but tonight we were out of them, and decided to just have sex without one. We've done this before and he always pulls out. Well tonight things got a little carried away and he didn't pull out in time and came a little inside me but pulled out for the rest. What are my chances of getting pregnant? Should I take a Plan B just to be safe? Or should I be fine and just not worry about it?