hi there,

I can only go by my own experience with my DS.

at 2 he could say mum, dad, and hot, that was it, occasionally he would say something else, but always a once off and never again.
I had sooooo many people at me concerned over his lack of speech, he was like your DD, nothing lacking in comprehension of the language just didnt say much.
when he hit 26 months, I was starting to get a bit worried, I was told to go see the MCHN who would refer me on to the right people, I didnt get around to it.
We went away over easter with all the family and lots of cousins, it was like almost overnight DS had the "word explosion" you hear about.
Now I can't shut him up, we have new words everyday, he copies almost everything I say, I even busted him singing the alphabet song the other day (he shut right up when he realised I was watching!)

So, if you are worried, going to see someone is not going to hurt, The earlier you do get on to these types of things is better from what I have heard.
Good luck xo