me and my boyfriend fooled around and I am a tiny bit scared that he had some sperm on his finger

Hi! I am 16 and my period is 4 days late. I only started my period when I was 14, and I've read that it can happen for a girl to skip a period or twoo in the first few years of having your period. About two months ago, me and my boyfriend fooled around and I am a tiny bit scared that he had some sperm on his finger when fingering me.. even though he was careful and washed his hands each time, I can't remember if he did so EVERY time. After this happened, I had my period about 3 weeks later for 7 days (normal cycle) and now (about a month later) - I am 4 days late