Relax man, you should be absolutely fine. The important thing is that you came out before ANY sperm went inside her. In that case, you are not in danger. If you think any sperm went in BEFORE you took your penis out, then there may be some danger but I still wouldn't panic. If you really worried she can go to see a doctor tomorrow and they may prescribe a morning-after pill, but chances are she won't need it.
For the future, use condoms, not the withdrawing technique, which is always a bad idea for this very reason.
Hope this helps.
Reading your post again, it sounds like you were never actually inside, so there's absolutely no danger. Relax and enjoy some more safe sex...