Late period?

My last period was way longer than any other periods I've had before, I'm 4 days late for my period, so could it be because my last period was long? Could that be why it's being delayed? I haven't had sex but I did like have a guy over and there was semen on my bed and I'm pretty sure I never touched it so I can't be pregnant 😂 but I can't help but stress about it ya know? I'm not too smart when it comes to this stuff😂 what other reasons could there be to why it's late?