Jjdjjdhdbd. Eujejejeuejrur
My purple pen is out of ink
As with any author's decision to use 1st person, her intention most likely -- in this story -- was to get her readers to go along for the ride into madness and cultivate a certain amount of sympathy for the narrator and her plight. The constant use of "I" puts readers in the narrator’s head and allows them to empathize with her.
The answer is allegory, since allegory is a rhetorical device that convey hidden meanings through symbolic figures in a literary piece which create the meaning the author wants to portray. It is in a form of story or poem and the meaning could be political or moral, depending on the author's true meaning.