UTI’s... At my wits end...

I’m at my wits end here. I am CONSTANTLY getting UTI’s. Like, every other week. It’s driving me nuts. The first one I had after I lost my virginity lasted 3 weeks and it felt like I was being stabbed constantly. It was awful. Since then I’ve been having them consistently every other week. I take all the preventative measures, peeing after sex (if I can’t do it straight away it’s usually after at least an hour), taking Hiprex daily/after sex (stops bacterial growth), drinking plenty of water/cranberry juice, and I’m even on anti biotics right now for the last UTI I had not even a week ago. Does anyone have this problem or have any advice for me? This never happened before I started being sexually active. Thank you.

Edit: Thanks so much for the advice guys!! I’ll see about putting those things into action