What are the chances of a girl getting pregnant when using a condom and pulling out?

Ok so me and my girlfriend are VERY safe. We have our future all planned out, and a kid would just CRUSH those dreams. Now I'm pretty positive she is not pregnant, but we both still need a bit of convincing... About 2 weeks ago, me and her had protected sex twice. Both times I used a condom, and made sure that it did not break. She even inflated the condoms to make sure no air was coming out. Not only did I use a condom, but I also pulled out BOTH times and watched myself "shoot my fluid" on her thigh. She is still very afraid though, so can anyone reassure us? or tell the chances or something like that?