well first off i'd sell one of those GK, you only need 2 max on the small chance your GK gets injured. i only have 1 GK as if he does get injured i can use packs to heal him.
i'd say you only need 3 ST max unless you like to play 3 ST up front, then you'd want an extra ST as a sub.
i'd sell an AMC too.
the way i work with my squad is i only ever have 1 extra player per position as a sub, incase of injury or if i want to sub during a game for rest packs.
so 2ST + 1 reserve
2MC +2 reserve
2DC +2 reserve
and +1 reserve for each winger.
but from what i can see with your squad, if you sold those un needed players you could pick up a relatively good MR/DMC with the money you'd earn