Gestation diabetes symptoms?

If you got diagnosed with GD, what were your symptoms if any? I am 27+ weeks pregnant with my third and have been having very bad dry month/thirst and peeing like crazy, and got a weird rash on my face that I think is impetigo(not sure, I never had it before, but my dad has and says that's what it is). Also I have only gained 6lbs this whole pregnancy, which is very weird for me, I have big babies have also gained a decent amount of weight during my pregnancies. I am not overweight. I did call my Doctor and they want me to come in today because they are concerned about GD. I'm just worried and not sure how likely it is that I have gd.