Back contractions v regular? Kind of a labor question?

I'm a FTM and I have no idea what to expect out of labor. Everyone always says "you'll know." When I say I'm good with pain "oh this is totally different - you'll feel it." Well, this pregnancy I got a kidney infection and had no idea for over a month (it caused a lot of problems). I wasn't in pain. I was completely asymptomatic. I'm 37+2 and today I have been getting sharp back pains that get tight for a while then go away. Earlier I started feeling like my abdomen was hurting fairly bad, but again, it would ease up and go away. There's no consistency to the pain yet so I don't know. Could this be like prep for labor? Start of labor? I'm so confused!