I'm 20 years old. I am sexually active. I have been taking birth control religiously for about 3 years now. Last month I had to get a urinalysis for a physical. It came back that I had a *slight* UTI. They gave me the medicine, which I started towards the end of my last period, and it cleared up in a few days. My period is 3 days late. What should I do, given these circumstances?