Preterm Labor?

Mari Ann
Severe low back pain, pressure when I stand or walk, swollen feet & ankles. I've felt like I need to poop all day and nothing is happening in that department. Just feeling very off. Baby is moving just fine, as much as usual. Any insight? I'm 31+5. My daughter came at 35wks, and it was so quick I didn't even realize I was in labor...thanks in advance!!!