Abandoning the doll like that seems a little cruel, but that could work with the story; perhaps this could be turned into a short horror story, where the doll speaks to her at the end, punishing her mentally or physically for abandoning the one who helped her through her hard times. Heck, it could stretch to a novella; showing her transition, only to show the doll ruining her newfound peace (hurting/killing family and friends? Dark but hey: horror) because of its abandonment.
Conversely, she could repair the doll herself (perhaps when she's an adult and happy) and end up giving it to another child who needs it. Just the two ideas off the top of my head. Definitely a good basis for a story here, though.