I find it really bulky on my 2yo, so you certainly aren't alone. While he's no heavyweight by anymeans (he's tiny lol) he's certainly bigger than 6kgs.

We're only on the second snap from the tightest. I've found that a higher rise on little guys is a much safer bet than a lower one and you do get used to particular brands of nappies. In terms of absorbency, the Candie far out strips the IB and is my preference, but I will put mine away for an older bub I think.