as you wore a condom then the chances are very very small.

in future though, if you want to carry on after you have ejaculated, the best thing to do is stop - remove the used condom and replace with a new one as semen can leak out of the condom after use.

if possible get her to also go on the birth control pill or similar (patch/nuva ring/etc) as back up in case a condom breaks or leaks.

props for using condoms