My body hates me

it just seems like everytime I have sex I get a UTI, I don't have sex often maybe once every two months, and yet the day after each time I feel like I have a UTI, I've had three diagnosed ones already and I have some pills left over from last time so I took those, but I just know I'm not supposed to feel this way after sex, especially since my partner always uses a condom and I take birth control, any advice???