Zissou, those pieces look great on you, man! You wear them well.
I deduce a couple of things: Your have a much slimmer build than I have. And you must like a snugger fit than I do. In some ways, this is what a medium looks like on me, but I don't feel comfortable there, mostly because I feel I need some room in the pits and the shoulders.
All this goes to say, I guess, that sizes and measurements are only starting points at best.