Something else that might help: try turning your mouse sensitivity up to about 90% or more in the option menu so it doesn't take as much hand movement to block or attack.
For most people i trained,
lowering the sensitivity was helpful and made it easier to accurately block. With too high sensitivity your camera is very unstable but more importantly: it's easier to block the right directions. I've noticed that with too high sensitivity, you sometimes block the wrong direction because the mouse is overly sensitive.
So look at sensitivity and see what works for you.