Sasha also says next to nothing. Her older sister is also 6, I'd not heard that 2nd children can be slower at starting to talk, thats interesting. She says 'dadda' specifically for daddy, and 'raa raa' for pretty much everything else. She says 'woof' if she sees a dog, and makes a particular sound for Jess (dd1's name) that seems to be just for her, but otherwise that's pretty much it.
She does however make the kind of noise that teenagers tend to make when they can't quite manage to talk, that kind of grunting eh sound. She does understand a lot though, like if I tell her its time to go out, she'll go and get her shoes and bring them to me to put on.