Worried About M

We didn't worry when M wasn't speaking at age 1, but now that he's fully 2 and not speaking, T and I are concerned. What is most concerning is not that he's not speaking words, but that he's not even practicing making sounds. W started babbling a lot at 18 months, although he didn't speak much until closer to 24 months. But M doesn't really babble.

M says one word with regularity-- "uh-uh". In the past few weeks he's added another, "uh-oh" which is adorable with his little baby inflection, and I hear that a few times a day when he drops something. If I cajole him, he will sometimes say, "mama," but other times he'll refuse and just shake his head and say, "uh-uh." I can't even get him to make sounds for me, like ba ba ba ba or da da da or anything. I get the feeling that he probably could make these sounds, but he is just refusing. The question is why?

If he is self conscious about not speaking as well as W and I, how do I get him to relax and just go for it anyway? Or is he self conscious because he really can't make the sounds? Does he have some sort of unseen defect of the tongue where he can't control it enough to make various sounds?

He doesn't seem to have any other developmental delays, and he has all the speaking "readiness" skills (pointing to objects in books, following oral directions, etc.) but he's just not speaking (except for his two words). We checked a couple of websites, and they universally recommended that if in doubt, get it checked out. So I've got a phone call in to the child development department, hoping to hear back soon.