i urinate alot

im 31 male that urinte alot. i been to the doctor but doctor but they seem to cant find out what wrong with me. i had alot of different test like my blood, uti, cystoscopy everything come back good. i been on diferent meds n the one im on now is oxytrol for overactive bladder, been on that for like two days dont seem to be working. i also have pain in the pelvic area most of the time. i dont drink alot and when i pee it comes out in small amount like 100 cc or less. the doctor say my bladder is not waiting to it to get full to void my urine. i pee soon as my fluids reach my bladder. he say im to young to have these problems and they dont no the cause of it. they just keep giving my different meds to try out. can yall please give me a answer to wat yall think thanks....