Signs of gestational diabetes?

Ana

I started off my pregnancy at about 100lbs and since then I’ve gained 20 pounds, I’m 26 weeks now and I’ve gained 4 of those pounds in less then two weeks! I go in for my GD scan in about two weeks but I’m kinda worried. My mom and my aunt had it for one or two of their pregnancies. Should I call my doctors office and tell them or just wait?