In Speak, what is symbolic about "Hairwoman" and the narrator's description of her?

Melinda, the narrator of the young adult novel Speak, describes her English teacher as follows:

My English teacher has no face. She has uncombed stringy hair that droops on her shoulders. The hair is black from her part to her ears and then neon orange to the frizzy ends. I can't decide if she had pissed off her hairdresser or is morphing into a monarch butterfly. I call her Hairwoman.

Melinda initially finds Hairwoman to be a bit too freaky, but gradually grows to appreciate her "warped sense of humor" and the super quirky homework assignments she gives to the class in order to engage them in the act of writing. 

When Hairwoman gives them an assignment to identify the symbolism in Nathaniel Hawthorne's The Scarlet Letter, Melinda comments that looking for this information is fun, "like a code, breaking into his head and finding the key to his secrets. Like the whole guilt thing."

All of Melinda's assessments of Hairwoman and the classwork that she doles out actually seem to be reflections of Melinda herself. Melinda hides herself much the same way that Hairwoman hides her face; both are deeply self-conscious and struggle with expression. Melinda's judgmental attitude of Hairwoman's appearance and Melinda's own attitude toward her body suggest that Melinda projects her negative feelings about herself onto others.

Melinda's commentary on the Hawthorne assignment also seem to be a commentary on her own desires--the wish that someone would break into her own head and unlock her guilt and her secret about the tragic assault she suffered through in silence during the previous summer. 

When Hairwoman gets a buzzcut, Melinda wonders:

I don't know what caused this. Has she fallen in love? Did she get a divorce? Move out of her parents' basement? ...I'm thinking she found a good shrink, or maybe she published that novel she's been writing since the earth cooled.

This interest in Hairwoman's shifting appearance (and the possible life changes behind it) also represents how Melinda has altered in the past few months. Despite her acerbic attitude, Melinda seems to want good things to happen to Hairwoman. This comes at a time when Melinda is gradually becoming more open to the world around her, even developing a budding friendship with Ivy. Although we cannot see how our narrator has been physically altered, her observations of the new "look" of her teacher might also reflect some new beginnings for Melinda herself.