Hi Prissy - just writing to say that you're not alone. We're dealing with almost exactly the same thing! I only wish I knew what might help! After much soul searching and research, we've decided on an online writing program and keyboarding. One of the things that we're also trying is the use of very explicit instructions laid out in quite a mathematical formula. For example... instead of an open-ended writing prompt that J is expected to write 1.5 pages... I've broken this down into specific guidelines:
* write 5 paragraphs
* each paragraph must have 5 sentences
* each paragraph must have 5 interesting and descriptive adjectives
* each paragraph must have 1 compound sentence

And so on. A friend also put my onto http://ywp.nanowrimo.org/workbooks J's teacher is looking at the workbook this weekend. I quite like the story arcs and I think they might help J understand more about structure.

Anyway, love to hear more about works for others...

jojo