Backing boats up into the water seems to be a struggle for most people, trust me I was right there with you when I was learning. Simple little tip instead of having your hands(or hand) at the top of the steering wheel, try holding the bottom middle of the steering wheel. This reverses everything in your favour, by simply moving your hand to the left, the trailer will go to the left as well, same goes for moving your hand to the right the trailer will go in that direction as well.
Use your side view mirrors as well, rear view mirror tends to cause issues and your entire body gets turned BUT by holding the bottom of the wheel and using the side view mirrors you remain facing forward.
Key thing to remember is keeping the trailer tire in the centre of the mirror lined up about 3 ft away from the dock you are backing into. This is a cool little tip that results in less confusion with the hands and directions getting mixed up.
Picture I posted along with this is just to show where your hand should be in the starting position.
The AMFisH guy…