My own ship takes a while to gain steerage going astern. If there is an meaningful wind, it really is difficult, particularly when reversing into a pontoon finger arrangement. I am happy to have moved to a longer dock for that reason.
In reverse, you can normally tell when you are gaining directional control as the rudder begins feeling "heavy", in my case through the wheel.
If the rudder is feeling "easy", it ain't steering.
If the ship you have is moving forward ok with the prop you have, I would be inclined to leave it as is.
Changing props doesn't always improve things.