Quote: chipolata @ April 25 2011, 10:17 PM BSTBut why - according to her big speech by the door - does he know less and less about her every time they meet?
Because he's a time traveller, and he keeps jumping around in her timestream as they meet, they're not meeting in a linear fashion. So the Doctor she first met when she was young is a Doctor who already went through all these, and other unseen adventures, with her. As she's got older, she's met earlier versions of him who would obviously have less experience of her, whilst her knowledge of him would be growing.
It's obviously just a dramatic device that he happens to meet this person in this fashion, so it's a bit contrived you could say, yeah.