Jappooh
At this stage, bb supposed to gain only 300g per mth. So don't worry.
My boy didn't gain any wt for 2 weeks and I was very worried. Then the 3rd week I weighed him, he gained 200g liao.
Anyway, Elvin seems to be eating a lot of food. Maybe you should slow down a bit if he's not hungry. I read in a child care book that if you stuff him food even when he's not hungry, he will get immuned to food, and will eat even when not hungry. This is the cause for many obese cases.