There may also be an organization that advocates on issues such as these. Dealing with the school district is a very hard thing to do. They put my dad in the back of the classroom because he couldn't read (I'd guess dyslexia). He probably has a reading level somewhat about fourth grade now.
You might try to see if there are any professionals in your area who works with learning disabilities.
As for your writing, it is better than fourth grade level. I am surprised that a theurapeutic school wouldn't be equiped for dealing with learning disabilities. That needs to be changed.
Keep learning as best you can. Try to get the help that you need. May you learn to your full potential and get a job that you can love. I am still trying to learn and find a job that I love and I'm 33.