Most people believe she’s only narcissist, but not quite. It is shown in the movie that she’s a child of divorce and, consequently, her father stopped caring for her to the point of not showing up in the hospital when she’s supposedly sick. Most likely, this abandonment could be the root of her need for attention.
After having seen a woman being attacked by a dog and having a taste of attention by disastrous events, she tries to get that attention back by self harming. It isn’t stated but it seems like she has Munchausen syndrome.
The movie also reflects on today’s society, how difficult it is to have a relationship with attention seeking people and how people will give you attention for a minute, but when it becomes a burden, they’ll just go back to thinking about themselves, which is shown when she has some sort of seizure and people are more concern about a law suit rather than her health.