I think the jacket fits fine. It's just that the sleeves are way too long (as H&M jackets usually are) and you are making up for it by lifting your arms up slightly so that they don't cover up half your hands.
By lifting up your arms, you are making the shoulders seem too big. If you stood straight with your arms straight down at your sides, I bet that your shoulders would fit fine and it would no longer look too big.....other than the sleeves of course which inevitably will need altering.
The suit is a mess and just doesnt fit you properly anywhere. The pants look like they are pulling on your thighs. The arms are to full and the sleeve and Jacket length is just to long. Save up your bones and go for a better made suit off ebay or salvation army.
That guy "the wizard of ahs" seemed popular around here some time ago for having decent wares at a low price point.
Never used him myself though.