Not helpful at all I'm sure but I am 36 years old and still hold my pencil incorrectly and start my O's from the bottom. I taught myself to read at age three and was beginning to write around the same time. By the time I hit school everybody was trying to change my grip (I put my index, middle, and ring fingers on top of the pencil) and my letter formation. I don't know if I was just too stubborn wink or what but it never did work. I always had marks on my report card about my handwriting and at least one teacher chalked it up to the hand not being able to keep up with the brain.

I am a nurse now and I was actually checking a patient in a couple of weeks ago who, it turned out, was a retired school teacher. She actually lightly scolded me for my pencil grip and it was quite obvious that it was taking everything in her power to not try to do something about it. My writing can be pretty messy but I can neaten it up if I concentrate on it.