i was with my girlfriend the other day and she gave me a handjob. about 4 hours later she blew me but i didn't come a second time(i also didn't urinate in between). i ate her out and then she sat on top of me naked. i was also naked but my penis was not that hard and it wasn't inside her. she was sitting basically at the base of my shaft and kinda moving forward a bit(like dry humping only naked). We cannot have sex until she gets on birth control because she gets way too paranoid about pregnancy. i totally gapped about it and then afterwards while she was sleeping (she gets really tired after orgasm) i was starting to get freaked out cause the last thing i want is for her to worry. should i tell her my concerns or is there even a reason to worry? when i came she wiped it up immediately and then when she blew me it was for longer than 30 min so if there was any sperm on there it would be gone right?.... i dunno i just care about her so much and i don't want her to worry... please any advise would be great. thanks
You want to know my gut feeling about this? If you're worried enough to ask then yeah, you definitely should communicate with her. And if you're worried enough to ask then if it's been less than five days since you had sex (remember "sex" isn't just intercourse!) then she should consider taking an emergency contraceptive.
So. How did I assess your risk? I went to the Scarleteen Easy Pregnancy Risk Assessments page. That has links to several sets of questions and answers about different kinds of sex that do a very good job of helping you decide what to do. Your specific circumstance was a little tricky since you didn't exactly have regular vaginal intercourse but that skin-to-skin contact made it much more than "dry humping." So I cheated a little and read those two plus the questions about manual sex (e.g. handjobs and fingering.) The upshot is that while the risk is low it's definitely not zero so act sooner rather than later.
One other thing I really, really want to stress, Richard. You say you "gapped about it," and didn't think about the pregnancy risk till later, and you wondered if you should share your concern. I'd like you to consider that you both did -- you're the one who said she sat on you, right? So it's not just you, you're both responsible. If one of you has anything to worry about then think about worrying about it together.