Don't cancel anything. That's painful for her and she learns to resent you. She cannot control this and it is natural. Learn to validate her feelings and support her through her excitement. She can skip breakfast, it won't hurt her one time. Go with her to her room and join her on her confusion about getting dressed. She is so excited, she wants to look perfect.

Validate her feelings and also let her know that she looks great no matter what she wears and that you love her. Learn to go with, not against her and she will
learn life lessons on her own with your love and support.

Like I said before, I have learned these skills from books and workshops. I attended teleclasses, read, listen to CDs... Parenting has to be learned. It is the hardest job on earth and we need to learn.
I mention books I like in other posts but choose whatever fits your aspirations.