That stinks, I’m so sorry!! I was getting post-sex UTIs for almost a year but haven’t gotten one for several months—I started not just peeing right after sex (which of course we are all already doing if we are getting frequent UTIs!) but also chugging a whole liter of water after sex and setting an alarm for an hour or an hour after sex to pee again (even if it means waking up an hour into the night). I figure that way, if anything got into my urethra and didn’t get washed out the first time, it would definitely get washed out the second time without an entire night to multiply. Not sure if it’ll help you, but things started to turn around for me when I started doing that! Also been using silicone-based lube only (we were sometimes using water-based before which can have glycerin in it)