Let's start with a picture of Joshua's coat from last year and the one we got him this year (shhh, it's his Advent train presents).
The little coat is a 2T, the big one is a large for size 4-5.
All summer Joshua wore 2T clothes. As the year got colder, I realized his long sleeves weren't long enough, and his pants fell above his ankles instead of below. So I moved out his 2T's and got his 3T's.
The 3's were too small, too!!
Here's the skinny - my son is skinny. He always has been. His length is, apparently, a 4T. His girth, however, is still a 2T. He's still wearing 18 month trunks for swim class, for goodness sake. So, all summer, T-shirts and shorts fit him fine, because, well, you don't notice the length so much for those. Come winter and it was very clear how much height that boy gained.
We ended up going shopping on Black Friday to get him and his little brother clothes. Sebastian, of course, can use his hand-me downs, but he is 9 months tall and 9 months round. As we get to each stage, I realize Joshua's odd sizing has left us shy of certain sizes, so we have to supplement. Which isn't a bad thing. Joshua has a mix of old (from his cousin) and new clothes. It's good Sebastian can get the same. :)