I'm so sorry you are going through this. I'm sure it's really stressful.
Here's a question though. Does your somehave problems with ear infections? I ask, because sometimes, even if they aren't infected, they reatin fluid which makes it hard for them to hear. Thus delaying their language acquistion. This happened to my friend's son. We go to the same pediatrician and before jumping to autism, she wanted to rule out all medical possibilities first. Turns out poor T couldn't hear. He got tubes and has experienced a language explosion. He went from 3 words at 18mos to speking in short sentences at 21 mos.
Anyway, it's a thought. I beleive in ruling out all possible possibilites before jumping to teh worst.
Jenny