If she is choosing to be homosexual and has not told you yet, she may a) still be a little confused about who she is or b) trying to slowly work up the courage to tell you.
And when she does, she could be a little nervous but even moreso about your reaction. Be there for her, love her, show her support if/when the time comes she feels no one else will be.
At that age we see 'mom' as our rock; be hers.
