You're my girl

My dad likes to tell me that I'm his girl. I'm his only girl but I'm not sure if he's saying:
1. YOU'RE my girl
2. you're MY girl
3. you're my GIRL
and I don't know how to respond to that either. Because if I say, "You're my boy." it makes me sound like we are homeboys, which would make me a boy, which would negate the purpose of his comment.
So...at a loss for how to respond, I figure it's usually just best to respond with the exact thing that he said to me. I mean, it works when I'm in trouble. So now when he says, "You're my girl." I just smile and say, "Dad, you're my girl too."