No Braxton Hicks??

I’m 31 weeks and I don’t think I’ve experienced Braxton Hicks contractions yet... I’ve felt a tightening pain a handful of times when I’ve gotten up too quickly from a stretch or tried to roll over too fast in bed, but I haven’t had multiple contractions over a period of time.

Is it bad that I haven’t felt these yet? This app seems to talk about them a lot, like they happen all the time starting in the 2nd trimester so I’m kind of worried that I don’t have them