I can't tell if I'm just having contractions or a UTI...

Mild cramping to random strong ones and when I need to pee it sort of hurts. I only have two weeks left and I'm getting nervous! My stomach feels tight and I'm up all night peeing. Definitely feeling pressure in the pelvic area. This is my first time so any advice would be helpful. 
Monday I'll be going in for a NST.