Frequent UTI’s

So I have been getting UTI’s every other month since I was 17.!!! I am 20 now. I have seen doctors and urologist and urogynocologist and no one has been able to tell me why. I keep proper hygeine, Always wipe front to back. I always pee before and after sex and I always wash up after sex because I know I get them so often. I even went 1 year without sex to see if maybe that was the issue and I still got them. I don’t hold my pee in and I stay hydrated.!! And whenever I get treated with the antibiotics I end up with a yeast infection from the antibiotics destroying my flora or whatever its called. Does anyone else have this issue.? I feel like there is something seriously wrong with me. I honestly don’t know what to do.