I'm in Bendigo, and I haven;t noticed them change. DS is over 13kg's and we use the red pack, the one I have at the moment says 12-25 kg, so the green should fit an 11kg bub fine, I also have a pack of the yellow here, that were purchased recently for dd that are 4-9kg and they are mediums.
just looked on the website and it looks like green is 8-16kg's
Aldi nappys come in small mediume large & extra large, pull ups and I think they are introducing a new born range as well, as I found some there before dd was born, and have a pack here to try.