Frequent UTIs 😩

I'm wondering if anyone can help me out. I'm 21 years old and I've been getting UTIs every 2-3 months and each one is more painful than the last. I shower daily, I make sure to use the bathroom as soon as possible after sex and I've refrained from holding my pee in when I feel the need to go so can anyone tell me why I keep getting them so often? Has anyone else experienced this before? Anything you guys can tell me would be greatly appreciated.