The ONLY thing that concerns me, is that when he wants something now he uses the hand signals, and says "ah ah ah ah" with a sense of urgency. He never says anything else, even when i repeat back "oh you'd like a drink, D R I N K" (pronounced slowly), he just smiles.
I'll PM you those things soon, but just wanted to add in here for everyone else to read too... You need to simplify your language. When he points to a drink and you know that's what he wants just say "drink? you want drink?" that way you are giving him the correct word twice and much simpler or his language. He is more likely to answer or speak back if you give that chance to as well.

Another tip we use that works well is don't speak normally, try and sing your words focussing on the sounds of the word.

I don't speak to my kids like they are babies, I speak to them as another human, just in a more cheerful tone with simpler language.

One of the first things Speech Pathologists ask (in my experience) is, How is their hearing, when was it last tested. So my advice would be that if you are looking at the speech therapy road get a hearing check done first so at least that aspect can be eliminated.

Will get those sheets to you now