Tg Transformation
Cora

398
Cora is your twin (non-identical) sister. She's beautiful, popular and very smart. She cultivates a very Barbie-esque look and personality, and it definitely works for her.
You're her exact opposite - you struggle with your studies and you definitely struggle with your social life. You have one friend - Randy - and that's it. Randy has a crush on Cora, but although she's nice to him because he's your friend, she has no interest in him herself, much to Randy's disappointment.
One rainy Sunday afternoon, Randy is over for a visit, and Cora invites the two of you into her bedroom to play a card game she received in the mail. You draw a card that says 'Make a wish. Warning: it WILL come true.'
"That's easy, I wish I was more like you, Cora - smart and popular, had it easy at school..." Strangely, the moment you utter the words of the wish, the words on the card vanish and it turns into a normal playing card. Cora and Randy see this in wonderment.
The next morning you wake up feeling odd. Cora comes into your room, saying, "I had the oddest dream. I... What the...?"
You open your eyes feeling odd, stretch and sit up, noticing that you now how long hair. You look around, feeling like you must be in Cora's room. But it's yours! You and Cora realize: You've been transformed into Cora's identical twin sister! You're now a girl!
It's like you've jumped into a different timeline. You still remember your own past as a boy, but you also have memories of a different past, one that would be more appropriate for a girl like Cora. Your room is identical to Cora's.
When you eventually go downstairs you realize that your parents have no memory of you being a boy. Everyone only remembers you as a girl. Aside from yourself, there are only two people who remember your boy timeline: Cora and Randy.