I'm 19, she turns 19 this week. This past Saturday, we were fooling around a bit (massaging her neck, boobs, etc.), and she asks me to get off on her chest. I get up and start masturbating, and I use my saliva as lubrication, but my saliva dried out fairly quickly, and, in the heat of the moment, I reach down with my fingers and insert them, briefly, to get some lubrication. When I came, we cleaned up everything, washed our hands, and dried off the semen without it touching her vagina.
I had a thought, yesterday, that I didn't know the chances that there might be precum on my fingers during masturbation, and that it would lead to a pregnancy since my fingers came into contact with the interior of her vagina.
It would've been when my penis was dry and had no lubrication, or not enough to cause pleasurable wetness with which to masturbate. At the time, I had ejaculated early that morning, and had urinated since then; after that, we got into some grinding earlier in the day prior to my ejaculation, and, while clothed, I had precum in my pajama pants. I ejaculated in the described way a few hours after that.
She's not due for her period for another week or so, so this is just me wanting to have any questions answered before we see if she has her period.
I know I'm probably stressing out way more than necessary, and I'm fully aware that if we're not ready for kids, we should be more careful. It was in the heat of the moment, and we are taking steps to prevent something from turning serious.
Thank you for any help.