About pregnancy. Pregnant. please help.

Yesterday me and my girlfriend had protected sex till she took off the condom.We had intercourse for about 1 1/2 hours.I ejaculated once and used the pull-out method.Before that I pre-cummed which I know is dangerous(especially since I masturbated earlier that day till I had an ejaculation,but I urinated almost immedaitely afterward killing most sperm,I hope) Anyway,her and I had sex and I ended up having an ejaculation inside of her during sex.Immediately afterward I made her cleanse herself.I didnt watch her but she says she used a dish towel and running water.I am not sure if it was a lot of sperm,a little or if she even got it out.Can you help me find ways to know if she is pregnant or how to prevent her from being pregnant.Please help. Thank you