Urine infection while trying to concieve

I am a 30 year old female trying to concieve. Every time I try, I get a urine infection, go to doctor, take antibiotics and get fine. In last October, the Urine Infection (UTI) was treated with three rounds of antibiotics. Doctors also did detailed ultrasound to rule out any stone or some other disease.

Further, doctor advised me to take a small dose of antibiotics after sex every time. I am doing this from last two months. Last month was fine, but this month, even after taking antibiotics, I am feeling some symptoms of UTI.

Anyone here who deals with UTI due to sex ? I am already taking cranberry juice and pee before and after sex. My husband also takes shower before we do the deed.