@AnUtterIdiot I've had GD twice now, once undiagnosed and once well managed. I felt incredibly well looked after that time and that everything was well under control. Have you been referred to the diabetes team? They were incredibly helpful to me, I had to test my blood sugar before and after every meal and by being really careful with my diet (with their guidance) I was luckily able to manage without taking metformin, although I got very close at the end.
Try not to be overly worried, when it's well managed the risks are really low. My DD's blood sugar was tested before and after every feed for the first 24 hrs and all was fine after that. I actually was very healthy and recovered really well as had had such good care taken of me. I know it's scary, but many people have a very similar tale to tell as me 
With my first it was completely missed as I was low BMI (despite the fact I had all the other markers) and DS had a tricky start as his sugars dropped so low after birth. He had a really high birth weight and was a natural delivery so it was all a bit scary. He has no lasting effects though so we were lucky, even with it being missed.This time round they are really dragging their feet with testing etc and I am pushing quite hard. I would much rather that like with you they err on the side of caution. I am sure you will have excellent care taken of you. If you have any questions though, let me know. Hopefully I'll be able to help!