I'm a left hander who was forced to write with his right hand in infant school, I didn't stutter before I went to school, but it developed in my first year at school, and it was awful. I stopped writing with my right hand and reverted to my left in junior school, around 12 years old. So now I write and play racquet sports with my left. I use a mouse on my right, throw right handed, play golf and cricket right handed, kick with my left and jump off my right leg. I'm left eye dominant for shooting. So weirdly ambidextrous. I lost my stutter, well 95% of it in my mid teens through a combination of breathing control and speech/ singing using headphones.  Best of luck to anyone trying to overcome their stutter/stammer.