It's interesting that, without the costume, Dina can't differentiate between Amber and Amazi-Girl. That tells you a lot about who and what she is.
To quote probably the only decent line of dialogue in an otherwise dire movie (Batman and Robin): "Am I Batman or am I Bruce Wayne? I'm neither... because I'm both." For Amber, the turning point will be when she acknowledges that, maybe, she isn't as compartmentalised as she thinks. Amber chooses to play the role of Amazi-Girl but it is her pain, her love of justice and her morality that Amazi-Girl enacts.