Preterm labor! How do you know?

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So I’ve read some women have had there babies early and they didn’t even know they were having preterm labor. I’ll be 32weeks Friday. I have never experienced true labor/contractions or my water breaking. I was always in the hospital already had epidural so never felt anything. I’m on my 3rd but 1st boy. Due nov 6th for c section at 39weeks. He’s already been dropped for awhile and sitting super low. I’ve been having a Sharp pain near my Left shoulder blade for weeks and Since yesterday(9-14-20) I’ve been having pain/cramping that goes into my sides. Today I have felt pressure in my bottom which I never get before. And lower stomach cramps on and off since yesterday on my left side as well. I have a dr apt this Thursday I’m trying to hold off until then. It’s uncomfortable but I also have a high pain tolerance. So I guess how would I truly know for sure or will I just have to wait and see what my dr says. I’m also working 2jobs and on my feet 24/7 so I don’t know if it’s just from that