My DD 16 has semantic pragmatic disorder which was described to us, by the speech and language therapist, as the hearing form of dyslexia. She has had to learn language very slowly and in the manner you would learn a foreign language. That said, she has a very good vocabulary but has to think each sentence through before she can say it. Her speech processing works differently from other peoples. As a toddler, if you asked her "What color is the rabbit?" she would think , rabbit, color, what. It's kind of like a spiral process to get to the target word.
Her speech is choppy but she can express herself quite clearly. When she was really small I went to sign language classes (Makaton) to help her learn to speak. The idea is that they use the signs whilst learning the words and then eventually can discard the signs when the words become second nature.....waste of time for our DD as she had decided that speech would be her method of communication.
Having said that, we invented signs to help her remember words for her French and English exams last year and she did REALLY well in them.
One thing we learned early on is, if asking a question count to 80 whilst waiting for an answer. If no answer is forthcoming then ask the question again in EXACTLY THE SAME WORDS. The reasoning for this is that although you can see it is the same question but differently worded, to them it is a completley new question with a whole lot of new words to be processed.
Chin up, you're doing all the right things, I'm sure.