Chorinic Urinary tract infections or more...I need a urologist ASAP?

Ive been having issues since I was about 13. It feels like i have a uti 24/7. It burns all the time, not only when I pee. Only a little bit of urine comes out and then it just burns. Ive been tested for UTIs, STD's, And everything but No one can ever find anything. The only way I can make it get through is to wear pads and when it burns I have to push out each lil batch of pee until its empty. BUT IT BURNS AND HURTS SO BAD!!! The pee is not coming out of my urethra, its coming out of my vagina. I know this because a urlogist had me put litle tampon like cotton pieces in there before I pee and then pull them out afterward to see if they were wet which they were. I cant wear tampons because they fill with uring and I leak. I dont know whats wrong but everyone keeps dignosing it as Overactive bladder AND ITS NOT!!! Its ruining my life and I need help.