Will Precum get my girlfriend pregnant?! its been 13days and

Hey im 20 years old and my girlfriend is 17, we had sex 13 days ago... it lasted about 15 minutes... i did not ejaculate because someone walked in on us, and a saw fluid on my penis and wiped it of with a towel when i jumped out of bed, but we did not continue sex after that...

Will that get her pregnant?!

and what should i do NOW ?!

please give me an answer... im very worried!

JoeyD