I was thinkin roughly about a lb more... from now till birth-day : ))
With my little boy I had scan around the same time. He was 5.12lb. He arrived on his due date weighing 6.2lb
The last couple weeks babies won't gain that much. Just watch your sugar intake if you're worried about weight. Just had my boy 9 days ago he was 8lbs 8 oz and came out just fine!
They can gain a pound a week in the last few weeks... :)
My boys only 13ounces :)