Hiya Whynaut
My opinion, 100% personal, is that your career must be the priority, although I totally understand and share keenly the importance of proceeding with your transition too. But it's rather difficult for any of us to perform our transition without money, and that's your career, honey :-)
Why are you stressing about the possible interview? If it's purely for professional reasons, well, I can understand, but if it's also to do with your gender, try to separate that out if you can. Put it in a box and leave it at home. They are looking to recruit a TEACHER, not a male or female or trans teacher, and they want a good one - you: someone knowledgeable, professional and confident, and gender is just one layer of who you are as a person.
Once you have the job, your priority must be to make your colleagues and students realise that you are a first-class professional and a solid person. And take your time to transition.
I know that it's hard to do this - hell, all of us just want to turn on our target gender as fast as we can, but it's a slow process, not just physically, but mentally and emotionally. One thing my age has shown me (I'm 45) is that we should try enjoy the journey instead of being hung up about where we want to "end up", since you never actually end up anywhere; you establish goals and head to them, but as soon as you reach them or get close to them you're dealing with the next part of life's journey.
Hope this helps a tiny little bit!
J