GTT and growth scan scheduled for 34 weeks

[Baz13]

This is my 3rd pregnancy, I have a 12 year old son and soon to be 8 year old daughter and it feels like it's my first time again!
I am 31+3 and after seeing mw yesterday was told I should have had a GTT at 28 weeks so being booked in asap; after measuring me she also said I needed a growth scan. (Fundal height measurement was 31cm, which is spot on for where I am really).

I remember having the GTT with DD but not DS he weighed 9lb 13oz (I put on 5 stone with each pregnancy), with DD I had a GTT test and all was fine but had a growth scan as fundal height was measuring 4 weeks above, I was induced and she came 2 days after her EDD weighing 8lb 8oz .

I have put on a lot of weight for this pregnancy (over 3/4 stone) and within the last couple of weeks my weight has crept on rather quick, despite being quite active. My BMI is on the high side, so that is the most likely cause for the GTT. But when I asked why I needed a growth scan, she said it was to check if baby was on the small side. (??)

My previous growth scan was pretty accurate with DD (although I know plenty of woman who have them and they are wrong). Has anyone had any correlation between GTT and growth scans, saying big or small babies?
Think I just need reassurance and love to hear other people's stories :)

[AGruffaloCrumble]

I had a GTT at 30ish weeks as I had polyhydramnios which is a marker for GD. It came back negative though. I did have a large baby (7lb 7oz at 38 weeks). My growth scan over estimated her size though. I don't think this is actually answering your question but I've typed it out now. Someone I know who did have GD had a 6lber at 38 weeks.