DS is 2.5 years old and for the past few months, I've been getting more and more concerned about his language development. He uses and knows a LOT of words. He can label things and ask for things he wants. He can talk about things in the past or future. However, when he talks about things he typically only uses one word at a time. For instance, he may say "balloon" and then say "sky" a few seconds later when he's trying to tell me "the balloon flew into the sky". He waits for confirmation after every word he says, to make sure we understand what he's saying. He goes on a lot of rants, but in completely incomprenhensible language. He knows his colors, some numbers and knows how to label hundreds of different things...
He had a check-up a couple months ago and the doctor was pleased with his development but did seem concerned that he wasn't using a lot of two-word sentences. Since his check-up, he has started using more 2-word sentences such as "all done" or "there it is!" but not much more than that.
All the fellow mommies I know who have children his age are using 3-4 word sentences, singing complete songs, etc.
Should I be worried?? I know he's behind in language development, but is he TOO far behind?