Hi Christie,
All of your fears are perfectly normal and understandable. And I can add #4! The fear that, after doing all this, going through so much, that you actually DO go back, retreat. But here's the thing: I don't know you well, of course, but I really doubt that you will go back, at least not all the way.
Yes, you may find that you actually want to live an "agender" life. And that's okay. Or maybe settle on one side or the other and move back and forth a little (bigender). Whenever. If you had not done what your are doing you would never really know what is right for you.
And, let's face it, none of this is static. Your feelings about what you need may evolve over your future years. That's okay too.
Thank goodness you have a good and protected job. Also, I keep reading about how younger people are much more open and accepting of everyone under the TG umbrella. So you have that going for you too.
Remember this, please: my gender therapist says that the journey is like riding a train, and there are many stations you can visit along the TG tracks. From time to time we get off the train to explore an area, and sometimes we stay. Other times we get back on and go further, and sometimes we take the train back a station or several. It's all okay on the TG Train!
Hugs,
Emma