Just because you have GD doesn't necessarily mean you will have a big baby. With my last baby I was diagnosed at 15 weeks with GD and was on insulin from week 16 (made for a very long pregnancy) and he turned out to be the smallest of all of my babies at 3600g (or 7lb 15oz) and 52cm. If GD is controlled then babies may not be too much bigger than usual. I cheated a bit this time as well, so I just took an extra bit of insulin to even it out.
That said, my first son was 3800g (8lb 9oz) when he was delivered at 37 weeks 3 days.
Good luck to you all with your BSLs. Just keep telling yourself that it will go away!