You realise after a moment, that's just your voice. That can't be right, you don't know any Chinese! Yes you do, you're originally from Shenzhen and you moved to America when you were 7. But... even if you were Chinese, that was a female voice! Well, of course it would be, you're a girl...
Starting to freak out, you pull the qipao off forcibly, and brace yourself against the mirror as you stare at yourself in it. You try to collect yourself- you're American and you're a boy. You say it in your head over and over, even pulling off your underwear to look at your penis and reassure yourself of it. But the magic of the qipao has already taken root in you, and there is nothing that can stop it.
The magic seeps into you, reaching back even prior to your conception and changing the people who bore you. A handsome Chinese man and beautiful Chinese woman appear in your head and you realise they are your parents now, your body slowly adjusting to fall in line with theirs. Your genetics are transforming, and you see the effects before your eyes- your skin tone alters to an Asian composition, your facial features and hair adjust themselves accordingly and even your body mass seems to change. A different person's reflection soon stands before your eyes, and the old you has vanished from existence.
All you can cling to of your old self is your gender. You're still a boy. But now this too succumbs to the magic, and you realise that not only were the sperm and egg that you formed from from people of a different ethnicity to before, the sperm you had formed from had an X chromosome instead of a Y. You watch astonished as your body catches up and you start to turn from male to female. The strangest part is, it feels good. Your nipples perk up and turn erect, and they seem way more sensitive and give you more pleasure than they ever have. Soft mounds of flesh form around them as you develop breasts, and it feels nice to have a big soft chest to be played with. Your figure turns curvy and you feel kinda proud of how mature and attractive it must look. Your penis starts to shrink away, and as it recedes it only turns more sensitive- it seems dumb to you to feel bad about not having such a big thing, since it gets in the way so much and this feels nicer. Your testicles tug up inside you and your connection to manhood turns to a connection to womanhood as they reshape into ovaries while your scrotum turns into a vagina. As you become fully emasculated, it just seems nice to know you're not a boy anymore. The gender confusion in you has vanished and you feel comfortable in your body.
Once the change finishes, you blush at seeing your naked body in front of you and rush to cover your chest and crotch. You pull on some panties and then put the qipao on. Hopefully Amber and her friends will think this looks cool, especially since they asked to see some authentic Chinese clothing!