Stupid mistake

Ok, I am 16 years old and it just kinda happened. My boyfriend and I had sex. It happened on Christmas and he didn't use a condom. I should've checked and I feel so dumb. I'm really worried because Idk if pregnancy is a possibility. I was on my last day of my period when we had sex, and the charts say I don't ovulate til January 6 or so. He never came in me, but I still worry about precum. I looked up everything I could, and all says I'm okay, but he never or peed before intercourse. I'm really worried sick, I just need some good advice so then I can feel somewhat better. This was the dumbest mistake I've ever made