Preventing UTI's after penetrative sex?

Hi! I recently lost my virginity to my boyfriend over the summer (we don't see each other much since we're at different universities, but we have a good thing going with a lot of trust and love). After having sex, I went to the bathroom to make sure I wouldn't get a UTI. Things started heating up again later though, and we both kind of wanted to go for round 2 -  we ended up not going through with it that time since I was bleeding a little from tearing my hyman. For future reference though, should I be making sure I urinate after every thing we do down there, or is it ok to double up - say like, have two sessions of penetrative sex - before I should go to the bathroom?