Calo, welcome. Your room isn't extremely small(even after you resized your post)and M22s certainly wouldn't be too much. Three of them across the front(since you'll have plenty of room beneath the screen there doesn't appear to be a good reason not to use the same vertical center there)should be excellent.
QS4s would appear to be adequate for that size room and should be separated as widely as possible(a little more than in your diagram), since they're side surrounds, even when mounted on the back wall.
