I'm the same as fatty! My 50th centile line makes just under 9lb, our lines are generated on the weight of previous babies (mine were 9lb at 40 weeks, and 8lb 2oz at 37-38 weeks)
I wouldn't take any notice of the measurements by the midwife, three weeks ago I was measuring 25cm, then 2 weeks ago 29cm, then this week 26.5cm despite being 28 weeks! Midwife said to ignore as it will change depending on position of baby, water etc.
She said the scans are more reliable but again not spot on, so don't get too caught up with measurements. They are really only a guide.
I suspect this baby will be smaller than my other two as I have a different partner who is shorter, but we will see. Also will not be going full term.
My GTT was clear.