Saying 'who I am is enough' means that the person saying this is happy or satisfied with themselves (how they look, their personality, their intelligence, everything), and that they don't need to change anything about themselves for someone else, because they are already great as they are.

非也 :) 我自知我是誰就够了.

I would have to argue that the person who says that is really not so sure. There had to be some doubt in the first place for the person to utter such a phrase. You dig?

I know who am I and that is enough.