You've put a lot of work into the AA and it shows, and looks nice except for some parts where you've done it. Unfortunately, I think you have more fundamental problems that might require redrawing and re-AAing some parts of the image. It's best to get feedback early, rather than when you think you're done.

The AA on the text is too much and makes it look blurry. The writing also looks sloppy, unbefitting of the more careful work elsewhere on the piece.

On Rei herself:
The clavicles are bony bits protruding from the body, but you've drawn them as dips (shadows cast from the lines).

You don't need to AA 45 degree lines like on her collar and on the outlines at the bottom of her hair and on her collar. It just adds a blurry look. 45 degree lines look smooth even when not AAed.

The shading on the hair does not appear to follow any light source or show the form of the hair. Think of Rei's hair as something of a sphere, whose surface is lined with locks of hair. That might make it easier to shade. Weirdly enough, this is probably a good reference to help you imagine it in simple terms.

The character has some of Rei's features (short blue hair, red eyes), but you haven't captured Rei's likeness because the proportions and expression do not resemble Rei. She's meant to look very delicate and fragile. Her face is not so narrow, her eyes are round and not set so close together (the larger the eyes, the more distance they generally need between them to avoid that look). Her neck is usually drawn thin to help convey that look of fragility. She usually has a calm and emotionless look, but in yours she looks angry.