Review on Calvin Klein Kids' 2-Piece Formal Suit Set by Lamar Marshall

My son is 8 and I bought a size 8. It was too tight at the waist (cannot zip) and hit him at the ankle. He wears a size 8 on other brands but his typical outfit is jogging bottoms and sweatshirts :) I think it's probably because the suit is more cut/tailored that it's too small. For reference, here are his measurements: chest 28", shoulder 17", arm 19", hip 30", waist 27", inseam 24". I'll try 10 and 12 and see if either one works better for him. The suit is of good quality and well made.