FTM labor question

I'm 35 weeks 4 days today and since about 7 pm (it's 1 am now) I've had a cramping in my lower abdomen. Its off and on but the reason I don't think it's contractions is because the first time it lasted for 20ish minutes then stopped for around 40 minutes, the second time I felt it it lasted about 16 minutes and then stopped for an hour and this last time so far it's lasted 22 minutes. My lower back hurts ALOT and every time it happens, it takes my breath away. I lay on my left side and drink tons of water but it really doesn't help. It just randomly starts and stops (which is why I sort of ruled out Braxton Hicks) my stomach also doesn't feel tight. She's moving around a lot so I know she's okay but what's going on? Is this preterm labor or just regular old Braxton Hicks? And advice welcome (: