Why do i have to keep going to the bathroom?

I never had to go to the bathroom often. I would drink alot of soda and coffee and i didnt have to go every hour,But just a few months ago I had to go alot. Everytime I drink water i have to go 15 min after drinking then i would have to go again 10 min later. ANd sometimes i have that little feeling of needing to go but not that urgently. I have to go every half hour or every hour and its so annoying. I went to my doctor and she said its not a uti, and if it keeps going on to go back. I already took a urine test, so what else are they going to do if i go back for another appointment?