Sounds like your prop is way aft and the torque has a strong affect on
the boat.
If so, I call it popping reverse, put it in reverse add throttle and
then quickly reduce throtle, and take out of gear. Repeat as required.
Just do leave it in gear very long. Have the rudder turned the way you
want to go. I learned this on my first single screw cruiser, and it
worked fine on my 30 ft. Hunter.