who does the narrator think she is at end of story?

This is really up for debate,

The reason why the narrator does not identify herself until the end of the story The Yellow Wallpaper, by Charlotte Perkins Gillman, is due to the fact that the narrative that is employed for the story is what is known as a "stream of consiciousness." This type of narrative is characterized by the narrator's exploration of the self and his or her role within the plot.

This being said, it is safe to argue that Jane had just discovered herself towards the end of her sanity period as a result of her stream of consciousness. She has had to uncover many truths and emotions in order to get there. However, she remains repressed. That is the final straw and what ultimately makes her lose her sanity completely.

Therefore, conclusively, Jane had merely just gotten to identify herself as part of a life that is not what she expects. She does the ultimate task, which is to tell herself so and accept it. The rest is lost in her mind.

The narrator believes that there are women creeping in the wallpaper and by the end of the story she is one of the women who came from that wallpaper.