My daughter, still quite shy in many ways, was rather like your daughter. She seemed to have not a shred of nerves when performing at an Eisteddfod , music exams, singing at weddings, all where she was the focus.

Even at work, where she was required to join Toastmasters for practice at speaking publicly, she did outstandingly well.

This is in stark contrast to me.

Maybe your daughter's disappointment stems from her previous successes, her having been coached by you, and feeling she had performed well. Who knows?

I actually think initial failure is the best teacher.