Period late....

So my period is about 3 days late according to glow, but it's never usually predicted my period to the day. I took plan b over a week ago, and I know it can mess up your cycle. The thing is, I have all my normal period symptoms (acne, tender breasts) except for cramps which I only get the first day of my period. I also think I have a UTI which I am going to urgent care for today. Do you think the UTI is delaying my period or the plan b? Or should I be worried that I'm actually pregnant?