[ ... she clenches a hand over her chest, and edges her foot back a little more, but ...

... as much as she hates to admit it, Vanitas might be one of the few people who can help her figure this out. But she can't give him too much information... ]

Speaking from experience, huh? What would you know about it? I bet you've never had anything like this happen to you. Sure, you look like Sora, but you've never looked like anyone but him.