I have had a lot of different mcn I have a 19month old who is just 10kg, so he is quite slender but average height. I have recently got some itti bitti d'lish and they are just wonderful. Not so sure how the sizing would go if you have a really chubby bub. I bought all mine second hand, also have a couple bits for bots minkee AIO and these are more generous with size and work wonderfully too.
Anyway good luck, I have been full time cloth nappying for 6 months now and it's so easy.
Nikki