I don't remember the exact number as I read this many years ago. However, I kept a misgender  tally of everyy time they misgendered the main character (especially after her transition where it's inappropriate to do so) and it was over 120. As a trans person this is incredibly upsetting to be considered good representation. Although, it is great considering it was the first ever young adult book featuring a trans character even at the time they should've known this was a poor way of showing a male to female woman's transition.
That being said, it is groundbreaking with that considered yet still horrible representation and should not be used to teach about trans people as it was in my English class (which is why I didn't dnf this book)