Too much weight not good during pregnancy ?!

So I’m curious now. I’ve always been petite 5’1 always weighing in around 110-114 tops. So far I’ve put on 31lbs this pregnancy and I’m 28 weeks 2 days (doc told me today that I’m measuring at 29 weeks though) so we’ll see. But second time I’m hearing that I need to slow down with the weight gain I laughed it off the first time because I’ve always been small and return to my normal size after pregnancy (this being my 4th) should I really be worried?! My kids all were born early as well my first 2 at 34weeks and my last at 36 weeks. I’m on progesterone shot to help this one stay in longer but I’m really wondering is this really of any major concern. I think I still look pretty small 🤷🏽‍♀️