I've had UTI's every month since last year, went to the doctors , they thought i had cyst but ...

I'm 18 and have many medicial problems but this the longest and painfull one yet. It all started last year around july. I start getting UTI's every month a week before my period. My period was regular each month. Finally after 5 month of terrible pain i went to the doctors, had test done, and a ct scan even. They schedule me for surgery because they thought i might of had cyst. I had surgery and the doctor told us that there were no cyst the reasons for my uti's is that my urthera was basically closed, he said i was most likely born with this condition. He went in and dilated my urthera to 10(which is the size of having a baby). He blew up my urthera and told us they procedure could work and hopefully my urthera stays open or you won't work. After surgery was horrible pain but after couple weeks i could finally pee without crying from the pain. Well Month or 2 later I started getting Uti'S again. It's been 5 months since my surgery and i'm still getting uti's. My periods are very irregular ive skipped feb and march. and have them diff dates. I don't know what to do , i've went back to my regular doctor and he just put me back on the same medicine i was on before my surgery for utis that never help. I have a urologist doctor whom did my surgery and had a follow up appt. I don't know if i should go back to him or maybe even go to a gyno.