Snowsuits

My guy is in 12-18 month clothes, just beginning to wear 24 month clothes. I am trying to find him warm winter clothes as we live in a very cold climate but I am having so much trouble with sizes! I didn’t realize a lot of cold weather brands stop at 18 months and go directly to 2T. I tried on some 2T coats and they are so large on him but I am afraid he will grow out of 18 months before the end of winter. Does anybody have and brands they like or suggestions? Or are places like Carter’s winter wear actually good for really cold weather? Thanks!