Trans teacher here, here's no 2 cents. Obviously I am a huge ally, and many of my colleagues are too, but not everyone I work with is. The majority of the trans students that I teach are not out to their parents, are not changed in school software, and importantly, not out to every teacher. It sucks to get deadnamed and misgendered, a lot, I completely understand...but my personal suggestion is to immediately get involved with a queer organization or find some queer friends and get the lowdown on who will be safe to tell. It only takes one transphobic ass of a teacher to "accidentally" out you at parent teacher conferences or in an email. If staying protected from your parents knowing is top priority, find a safe community instead of a blanket coming out.