Had sex with boyfriend for the second time...got UTI. HOW do I avoid them?

Hi everyone

I had sex with my boyfriend for the first time in March. We are long distance and only got to do it twice. We just saw each other again in September for 3 weeks and had sex daily for a week. We used condoms and I was bleeding the whole time because nexplanon.

I peed after intercourse every time and...got a wicked UTI. Three weeks now and it still hasn’t gone despite antibiotics. Now I’m terrified of having sex again when I see him in a few months! We couldn’t have sex after that because of my UTI and now I’m worried it’s just going to keep happening every time we have sex, and because we don’t see each other for 6 months at a time, I can’t even figure out ways to avoid it. I just read always pee after sex. I did that within 10 minutes every time, yet still got a UTI.

Any help please? I’d appreciate it so much