This is HUGE and very very good. See if you can ignore her just a bit, like maybe she's a stranger to you but a very good friend of a very good friend....how would you treat that person? Treat her like that so she's not overwhelmed AND she wonders WTH?
And you played it right....I'm going no matter what. And you had to ask this morning to let the sitter know so maybe she could pick up another family to sit for.
As W acts not overly enthusiastic, I think it's an act. She has to not get excited to go out with YOU, oh my goodness! But I bet she's thrilled. And the "I'm not sure I want to go"...."I'm tired" (and what's that go to do with tonight if you're tired yesterday?).....all of that is her wanting you to beg her to go. And you didn't.