This is one of the things that has me on the fence about whether or not she's really in this to protect people, or if it's just something to be a feather in the cap to her, but hearing her admit her selfish concern, and being able to see that she does actually seem to feel guilty about it, makes the former a little more plausible. Even if she isn't really a hero yet (and, no, a few heroic acts do not, a hero, make. 'Hero' is a mindset. And attitude. A purpose. A way of life. It is not a few deeds and a fancy wardrobe.), there is definitely potential for her to be one, which makes her a little more likable to me.
I'm with Subaru. She knows she's not perfect, that she can be a real bitch sometimes. She recognizes the distance between herself and the hero that Max and Marisol want her to be. That she is worrying about not living up to that, and feels responsibility for the massive damage her power can inflict, says something good about her.
At the last, especially over this chapter, I have come to see her as someone who is not a paragon, who is not a hero, but as someone who is trying to live up to that ideal, and to live up to the responsibilities that she has taken on. We are rarely ready for the trials that life throws at us, and the most we can often do is gamely step up and try to get through them.
As a general rule, someone worrying that they're not good enough is a pretty positive indicator of their moral fiber. It's the people who are convinced they're righteous no matter what, and those who just plain don't care, that one ought to watch for.