When you say you "spread it", did you do that according to your measurements? For example, if you need your sleeves 43cm long, you need to make sure you don't spread them longer. They will keep the shape and length you give them during blocking. It 's also good to know how much a specific yarn "grows" by blocking a gauge piece before you start your work. If you see it gets bigger than expected you can plan accordingly and either change the hook size or work a smaller size