My house was invaded on my birthday by two workers from the local Infant-Toddler Program. I spent the two days beforehand cleaning furiously, because I equate a visit with this government-funded agency with another government-funded agency (SRS). (You know they'd report me if they thought I was neglecting or endangering him/them!)
It turns out all my cleaning was for naught, because they didn't even set foot inside. The boys were playing outside, so they just sat at the picnic table to observe him.
Even though I didn't really want them there in the first place, I don't think they did a good job of observing him. We watched him from 20+ feet away as he played on the swing, slide, and sandpile. I answered a bunch of questions about him - all truthfully - but they didn't really do much up-close observation and interaction.
They use a method called AEPS, and it has a scoring system based on how I answer their questions. He has to score below "10" to qualify for "intervention", and he scored 11. I think they also said he had to be delayed in 2 areas in order to qualify. So, like I thought, he is behind, but there's not anything they can do about it.
Basically, they told me to keep doing exactly what I'm doing. Lots of repetition, reading, interacting, and try signing if he gets frustrated (which he is not interested in at all). They suggested I try strengthening his mouth and cheek muscles by making him use straws (with thicker liquids like yogurt and applesauce) and whistles.
I think I would be more worried if he were frustrated at all. But he just seems to not care. He's perfectly content using his "words" and sounds. We understand what he wants and needs. There's just too many more exciting things to do when you're 20 months old!