Nice work, (expect a full review tomorrow from my signed in account)

The idea is good; the execution isn't. You need to add motivations to your characters, and make them more real. They're flat. They don't change. Your protagonist needs to change emotionally and grow in maturity over time. The contrast between that phenomenon and her youthful body should provide the conflict in the story. Read more short stories. I recommend Clarkesworld Magazine. Watch how the authors develop their characters in a short space of time.