Bravo on the Pavlova :)

... it is very noticeable watching people who haven't seen her for a while interact with her. They tend to firstly treat her as much younger than capable and then straighten up when she replies with more complexity than they are expecting.

A compliment to all more than a problem I think. I don't see the point of the 'goo-goo ga-ga' chat to a child, even if they cant put words together yet - surely this process will take longer if you aren't talking to them with anything that makes sense.

Hopefully she will be feeling better for the real birthday, and the balloons are still buoyant :)