Is my character a Mary-Sue?

Here's some info on her:
Name: Io, named after the moon of Jupiter
Age: Barely 15
Personality: Rebellious, hot-headed, clever, caring if you earn her trust
Flaws: Temper, doesn't think before doing something, antisocial, cruel at times, paranoid under stress (her uncle says she cracks like an egg)
Powers: Courage (has to build it up), good comebacks, clever. Able to resist the common lust for power (this is her greatest power)
Small Bio: Mother died when she was 2, raised by her father and Uncle Romulus since. Not popular at all at school. Fairly Environmental, vegetarian at times. (I'm not giving too much of my plot away here)