I am a virgin, but he touched me and there was a cum on his hands

I'm 15 female and a virgin. I have a few questions and I need some help/advice. I'm worrying myself possibly for no reason. So my boyfriend had a boner and he put his hand down his pants to I guess fix himself and he did not fully ejaculate, I'm guessing he had precum around the tip because he was a little wet. He touched it but there was a tiny amount. He took his hand out of his pants and then he fingered me. He said he had nothing on his fingers and if he did he wiped it on his pants. I'm not completely sure if this is true. I trust my boyfriend and he said he would never touch me down there with any type of bodily fluids. If he did had a tiny bit of precum on his fingers and fingered me about 2-4 min later is it possible I can be pregnant? I don't think I was fertile that day either. I don't have any symtoms and it's been a week. Is dried sperm dead? Is it possible to be pregnant from my situation ? My period is supposed to come in two weeks and a day and my stress is eating me alive. I'm afraid it's gunna come late or not at all. Please help thankss:)