UTI question

I feel like UTI’s are just one of the things I’m most afraid of in pregnancy, but I see all the time on here women who didn’t know they had one and were diagnosed or had some complication because of it. My question is- how? Does pregnancy change how a UTI feels? I’ve had them before and they are MISERABLE, I can’t imagine not knowing I had an infection like that. If the symptoms aren’t the same, how do you know if you have one before it’s too late?