DS is nearly 18 months and he doesn't really speak much. I mean, he chatters on all day but not much in the way of recognisable words. He says "all gone" and a cross between "hi" and "bye" which does for either.
He knows loads of animals, but rather than saying the name of the animal, he does the noise. He's got loads of these noises and it's very cute. He also understands most of what is said; if you ask him to point to a part of his body, or to get something, he does.
It's not something to worry about, this lack of "proper" talking, is it?