How many sperm does it take to fertelize the egg? One right? So emagin how many spermys were in that small amount? Surely more then one. So yes, it is possible to get her pregnant. Granted the chances are still smaller, cause it also depends on when this happened. If around her ovulation, then chances are higher. Next time you should use a condom, or make sue she gets on some kind of birth controle. Does she know you ejactulated a little inside of her? Some woman get pregnant even when the guy doesn't cum inside her, all it takes is the small amount of spern in the pre-cum. Which is a lot less then what you described. Good luck buddy, and hope she isn't pregnant!
Stacey