Chronic UTI

Since the day we got married I have been having UTI everytime we have sex. I have done like a hundred of urinealysis and cultures. I even had a CT scan to check if I have a reflux or blockage etc. it came out fine. I'm literally SUFFERING. I blame my chronic UTI's on the poor use of antibiotics. I remember the first time I had UTI the doctor didn't even bother doing urinealysis and prescribed a short period of antibiotics that didn't kill the bacteria so it became stronger and stronger. Anyways to those who have or have had chronic UTI's any substitute to the antibiotics ? Any tips ? I know about all the hygiene and cranberries you name it,I tried them all all!! It's affecting my marriage and now I HATE sex because I know I'll get UTI the next morning.