The Passing Playbook by Isaac Fitzsimons

Fifteen-year-old Spencer Harris is a proud nerd, an awesome big brother and a Messi-in-training. He's also transgender.
 
After a year of bullying, Spencer gets a fresh start at Oakley, the most liberal private school in Ohio. At Oakley, Spencer seems to have it all: more accepting classmates, a decent shot at a starting position on the boy's soccer team, great new friends, and maybe even something more than friendship with one of his teammates.

The problem is, no one at Oakley knows Spencer is trans - he's passing. So when a discriminatory law forces Spencer's coach to bench him after he discovers the 'F' on Spencer's birth certificate, Spencer has to make a choice: cheer his team on from the sidelines or publicly fight for his right to play, even if it means coming out to everyone - including the guy he's falling for. 
 
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'A sharply observant and vividly drawn debut. I loved every minute I spent in this story' - Becky Albertalli