Can a girl get pregnant without sex and the guy ejaculating?

So my girlfriend is a little worried that she might be pregnant. Her breasts feel tender and she's been having some mood swings. The first day of her last period was April 22, 2011 and she started having these feelings yesterday (May 7, 2011). Last time we "fooled" around was on April 30th and her cycle usually runs for 26 days but she's has had cycles that can range anywhere from 21 days to 32 days!!! We think it's too early for her to be having the symptoms she's having, but the only thing is we don't have sex!!! The most we do is rub our genitals together, but there is no insertion and there is no ejaculation either. If she is pregnant, the only way is if my pre-*** had sperm in it and it found its way to her vagina otherwise we're just panicking. I reiterate that I did not ejaculate near her or even around the time I was with her. Whenever I do ejaculate I make sure I'm far away from her and that I take a leak before I get close to her. Bottomline, is it possible to get pregnant simply by rubbing genitals together but without any ejaculation? Is pre-*** that potent???