I don't think there's anything particularly wrong with this query -- you've done a great job of laying out a straightforward run-down of the premise -- but I'm not sure it's doing you any favors, either. These of course are my personal impressions and opinions, but:
1. I'm assuming this is an adult novel, since you didn't specify MG or YA? Only a twelve-year-old protagonist is an awkward fit for an adult narrative: I know a lot of fantasy books where the protag started that young, or younger, but only in order to follow them through adolescence into adulthood, which it doesn't seem you intend to do here. But 12 is definitely not a good fit for YA. It might work for MG, though the wordcount is a stretch, and certainly the approach in the query is MG-ish, so... yeah. You might want to specify which, just to be clear, and also once I know which I might have a few more suggestions, depending.
2. Character, conflict, and stakes -- I'm not seeing them. All I know of Wendi is her age and that her mother is dead. I don't know why she dislikes her city, is she running away our of despair or for a lark; I don't even know what flavor of racism she's facing at school. (Or even if it's directed at her, or just bothers her in general.) Not much of the query gives me a sense of Wendi and why she's the main character, as opposed to someone a very interesting story is happening around. What is Wendi attempting to achieve, for herself? What is she trying to avoid?
There are conflicts mentioned -- Peter's secrets, Hook's intentions -- but they're external and unconnected to Wendi, so they don't give insight to her as a character and, honestly... I don't find them that interesting because they don't add anything new for me, a reader who's familiar with the Peter Pan stories. Which leads me to...
3. I would encourage a lot more specifics. There have been a lot of Peter Pan re-tellings in recent years -- including a steampunk-ish movie prequel story -- and some of them have been very successful. That doesn't mean there isn't room for one more, but you might want to concentrate on what makes yours stand out. For instance: you say it's a steampunk retelling, but how does that become an integral part of the story? The query mentions magic necklaces, which are more fantasy. You also slip into vagueness here and there -- "a second chance," "many secrets," "how much she will sacrifice" etc. -- which might build atmosphere but doesn't actually reveal anything about the plot. I know this is a story about a girl who runs away from home only to encounter more dangers and troubles -- that could describe any NUMBER of books. What happens in YOUR book? I don't need to know every detail, but a general idea of what story I'll be reading/requesting (if I were an agent) might be nice.
Hope this was in some way helpful.