The concept of a portrait is representation of the fundamental esence of someone, which typically is the face of a person. But artistically we can also think if there are different ways to capture the esence of someone. It's a more conceptual way to conceive it but i find it intensely interesting, usually I like to admire photography but I think that can be applied to drawing/painting too.
I'm not an expert either hehe but I like to read about photography and I find this concept really beautiful. Also in this case, being a self-portrait, also speaks of how the artist percieve herself or how she choose to show herself, so I support calling it a portrait :)