Sorry to hear about your high GTT result.
I never thought I would have had diabetes myself, but I do.
I even lost all this weight before I got pg and was a nice size. I ate pretty well and played sport, etc. So this diabetes stuff that I found out at 10wks was such a huge shock.
My baby isn't really any bigger then my first baby when I didn't have diabetes.
So maybe the baby just did have a growth spurt or some people just naturally have bigger babies. I'm not sure, sorry.

Try not to stress and worry yourself over it (I know it's easier said then done.)
Good luck with the 2hr one. I'm sure it'll come back fine.

Big hugs!!
xx