Our DD was similar to yours, OP. At 18 months she had almost no words and even right around 2 her spoken vocabulary consisted of just a few things like "ba" for "ball." Our pediatrician suggested we could look into speech therapy, but also said since it was clear she was understanding everything we were saying we could just try giving her more time. We never did speech therapy and now at 3 she has a fine vocabulary, perfectly normal for her age (and she chatters all. the. time. now). So, just to say I don't necessarily think you have to worry yet. Most of us get there in our own good time.
