My kid is a lefty and I assume she will eventually turn the page, because while writing the hand covers the letter in progress. That explains why all the left-handed people I met have rougher hand-writing. You might want to start a new thread about ADHD and left-handedness — I know I will be interested, and you will probably get more responses.
I assume you are familiar with Julia Cameron’s creativity writing (“Artist’s Way” and many others). If not, you will appreciate it. I found here morning pages to be the most effective tool in getting the emotional effects of criticism out of my head so I can get a fresh perspective. Over time I put a lot of work in stamping down my excessive perfectionist tendencies, and my new mantras are “Done imperfectly is better than not done at all” and “Quantity leads to quality” (which may not be true for others but it’s true for me).