I'm wondering about your vision and if you have neurological/muscle problems in your hands.
The only students I've ever had with long-lasting problems like you describe were a precious young lady with MS (I finally had to stop trying to teach her in my shop because I was so worried she would seriously cut/hurt herself and my insurance might not cover her) and my own mother at 89 years old with serious, deforming arthritis in her hands, and a lack of patience (I also wonder a bit about her vision). In 30 years, other frustrated students have improved with helpfully critical observation, patience, and practice.
I wish you well in handling your issue.
Jan in VA