Diabetes Mellitus and the urge to urinate

I have been tested for UTIs, had pap smears and pelvic exams, but no one can seem to be able to figure out what's wrong with me. It is incredibly uncomfortable, and makes me short-tempered and irritable. There is no burning or pain, and no other symptoms that I have observed- just the constant feeling of having to urinate. I have been in a monogamous relationship for the last 6 years, and have not had sex with anyone else during that time. I do have a history of UTIs but have not had one for a couple years, and take precautions to avoid them. Are there any specific conditions that I might possibly have and should be tested for? Are there any possible remedies I can try? I am at my wits end and just want some relief from this horrible feeling!