This went on for a few years and at the same time we were doing Makaton sign language with him. Over time he developed a means of saying 'Yes' by clapping, it was this definite yes sign that helped for our next level of communication, which was also asking him direct simple questions and getting an answer of YES or a non response which we took to be a NO. He was still doing great choosing using the simple choice boards as well.
But this is when an SLT (Speech Language Therapist) also came into our lives and things started to change. Also we purchased an iPad2 at this time and put a basic AAC (Communication App) on it. We never told the SLT we had done that, we just put the App on and setup a few basics and modelled with our son to choose the items on it. He couldn't manage the dexterity needed to touch the buttons on the App but again we kept helping him and did educational play (cause & effect) till he got the idea of how to use his hands on an iPad. I will leave the rest of the story for Part 2 - Next Level