Can't do it

Ana is 17 months old. 

We already know she's the size of a 2 year old.  She's been wearing 24 month and 2t clothes for months.  Now I guess she thinks she better act and talk like a 2 year old too.

I have a degree in Child Development and worked with infants and toddlers for years.... but I still can't remember if most 17 month olds use this many words.  Zoe talked a lot... but not this much.  Is it a 2nd child thing?