I think that SAHM is right on target.
(And I am parenting a teen-- one with a lot of similar/related issues, which all tie into self-esteem, perfectionism, and anxiety. No way to separate them.)
My predictions, based on what I've learned in dealing with my own perfectionist:
a) what would she study? No real answer, or not one that makes ANY sense, or doesn't shift like the tides. Because she has no desires/identity separate from the perceived approval/affirmation she gets from meeting the demands of OTHERS. If you probe, you may discover that she does NOTHING that doesn't have a 'payoff' in terms of self-esteem. My DD's thing is doing things that make OTHER people happy-- her friends, mostly, but also her perceptions of what everyone in her life "wants" from her.
b) Why? Because... she... just... wants to. I'm guessing that she won't HAVE a good answer for this one-- not one that she'll tell you out loud, anyway. So ask "how does it make you feel when _______?" questions. THOSE will be eye opening if you catch her in a self-reflective mood. (I know that I was pretty shocked to learn that NONE of her awards or achievements mean anything at all to her; to her, it was all "Meh." We posit that the reason is that an A/A+ is just "adequate" in most of her classes because they just aren't THAT hard-- for her, I mean. She values what she WORKS for, but at the same time, she's learned that NEEDING to work means that something is wrong. Not a good combination.)
Also ask her what makes her HAPPY. No-- really HAPPY. Not because of what she GETS by doing it-- an activity which IS its own intrinsic reward. Something she would do purely for the joy of being engaged in the activity. I was horrified when my DD basically couldn't name anything that she did just for herself.
I mention my own DD's responses to some of those things because I know that those things are perfectionism run amok in her case-- just without the outwardly-directed component that your own DD seems to have. But the socially-prescribed component is the "people-pleaser" type, and the workaholic, high-achieving version is self-oriented.
