"How long have I been with 'im?" Amy parroted. "Well..." Now isn't that the toughest question to answer. "I met him when he crashed into my garden when I was seven, and then again when I was nineteen, but I didn't start traveling with 'im until about a year ago. Dunno how long he'd been alone before we met. Like I said, he had just, yanno, changed or somethin'. He was making even less sense than usual."
The thought of getting together with the other people on the boards who'd claimed to know the Doctor (or someone calling himself the Doctor, at any rate) had occurred to Amy before, and she had no real logical reason for having not done it already. If she had to blame something for her hesitation, Amy supposed she would have called it jealousy, of the same sort that she felt when she first met River. For her whole life, the Doctor had been her friend (imaginary or no), and the concept of having to share him with someone who quite possibly knew him better was still new to her. Yes, conceptually she understood that in his long, long life he'd known many more people than little Amelia Pond, but knowing something and acting accordingly were two separate issues. Sooo, she skirted around that particular question of Donna's, moving instead to the next one, about River.
"I take it you've met River, then? Doesn't sound like you have any more clue about her than I do. She shows up out of order, like when I first met her wasn't when she first met me." Amy shrugged. "Time travel," she said, as though that would explain everything. "The Doctor knows her more than I do, I think, but not much more. I don't think any of us really knows who she is yet, but my money's on wife. She calls him sweetie, can pilot the TARDIS better than he can, plus," Amy winked at Donna and threw Tonks a smile, feeling slightly bad for leaving her out of the conversation entirely, "they flirt constantly."