I would say, decide on something you feel won't make it too difficult for yourself. It's a new story, a new character, enough challenges as it is. That's how I see it anyways.

I can totally see the appeal in portraying a character with a disorder of some kind, but you could take the milder approach to it like Cyclothymia. It allows you to get away with more, it leaves some room for maybe unintentional mistakes, inconsistenties.

For Malena her confidence is a major issue. I wanted something I could relate to without it overwhelming me with the pressure to do it "right" She had a sheltered upbringing, being told your too kind, too pretty in effect brainwashes you. That and her small stature are her only weaknesses I noted aside from her power. You'll discover more once you get to know your character a bit more and you can add to the sheet as we go along.