How likely is it that my girlfriend can be pregnant?

My girlfriend and I were making out one night in my car and it got a little heated. I was already turned on and then she moves my hand towards her vagina. I start to finger her as we're making out and I got a little too excited and came in my pants a little. We had to stop so that I could take her home so she wouldn't get into trouble. On the 15 minute drive home I touched my jeans under my crotch to feel for a wet spot a couple times. Whether it was a wet spot or sweat from sitting i dont know but it was not very wet. I wiped my hand on a dry part of my jeans and forgot about it. We then pulled over a few blocks from her house and began the whole thing over again and I fingered her with that hand. I'm a hypochondriac and worry like hell over ANYTHING. Is there any chance that a little bit of *** may have stayed on my finger and gotten her pregnant? I'm going to be a senior this year and KNOW i am not ready maturity wise or financially to have a kid. And she is pretty pro-life and would most likely NOT consider abortion IF she was pregnant. I feel like an idiot. It's just really bothering me and freaking me out.