The chances that she is pregnant are very low. Here are the reasons why.
1. Even if there was precum inside her, it's very hard to get pregnant from it. Precum does not actually have sperm in it. The sperm that could exist would be from your last ejaculation. If you had urinated after your last ejaculation, the chances of getting pregnant from precum are almost zero.
2. You did not ejaculate inside of her or on her vagina or vulva. This means that the vast majority of your sperm (if not all of them) did not enter her.
3. It is actually harder to get pregnant than you might think. You would have to have penetrative unprotected sex within about five days of her ovulating. If you want reassurance, you can ask her where she was in her cycle---that is, when she had her last period. About two weeks from the first day of her last period is when she would be most fertile.
While this is unnecessary, if you both are very worried that she may be pregnant, you can get Plan B One Step for fifty dollars from Walgreens, Walmart, CVS, etc. It is 89% effective at preventing pregnancy after unprotected sex if you take it within 72 hours of it happening. Seems like a pretty big waste of money in this instance though.