UTI ?

For the past year and a half maybe I've been having symptoms of a UTI that come and go. Mostly during the school year and in the car I would have the frequent urge to pee. Now if you realize, I mostly have that urge when I am somewhere that I am fully aware I can not just get up and pee. So I was thinking maybe it's something in my head, sorta having to do with my anxiety? Because I do not need to go when I'm at home or somewhere when I can pee whenever I need to. I've been tested and even taken non prescription medicine but I've been told that I don't have a UTI? Anyone know what to do or have experienced this?