15 is the age of development in sexuality and the best thing you can do is support her and how she is discovering and reaching these peaks.

I always believe it unfair to blame sexuality identity on hormones, we don't blame straight childrens sexuality on hormones and illness, do we? This is typical actually. And the fact that she is being open about it is fantastic!

Let her be her. Let her discover, change her mind, research, change the way she dresses, just be there. It's the best thing you can do!