BooBoo,
My son has and to some degree continues to have a similar attitude towards writing. We did do the whole evaluation process and found out that he is dysgraphic with 2 primary problems. First the physical act of writing quickly becomes painful. Second like you described, DS cannot keep all his ideas in his head in order and get them out in written format. The fact that he is getting things out in a bullet point form is actually good. He may benefit from using a graphic organizer of some sort and then putting together the draft. We use the computer for the bullet points and sometimes the rough drafts. It took 3 years of asking to get the school to allow him to keyboard some in the classroom so I hope you can do better.
If the act of writing is physically painful, asking him to practice writing may not help you overall. We learned that the hard way frown Then we let DS play around with a word processing program to tell his stories or he recorded them on a tape recorder. Even though he wasn't handwriting them, this gave him more confidence in his ability to process his ideas. Over time...A LONG time...it has improved. Also as he gets older they do more work on the keyboard in the classrooms which has helped alot.

Good luck!