My period is over a week late, could it be Plan B?

Hi everyone. I hope you're all as safe as you can be. 

My period is usually on the 10th or 14th of the every month. I'm over a week late as the title says, and I've already taken two pregnancy tests, both negative. The guy didn't ejaculate inside me but some of his *** was outside my pussy...excuse my french. Could this be from the Plan B? I'm getting eally concerned now as I was just going to let time go by and see. I read on reddit some users reported the same thing happening to them. Any thoughts/advice would be appreciated. Thanks.