Wow, can I relate to your story – the refuge of drawing as a child part especially! I think that childhood hyerfocusing is what allowed us to develop and sharpen our skills so much!
On not finishing stuff:
I once developed a practice of doing smaller, simpler pieces that I would start at a specific time in the evening and finish that night. They would be kept simple, so I could finish them in a reasonable amount of time. The effect of completing 1 small piece night after night helped immensely!!