At a certain point where you start getting at least reasonably confident in your passability, you kinda just stop thinking about it. And frankly, that isn't even necessary. If you keep living your life, eventually it just becomes normal. I was too terrified to even leave my car the first time I went out in "girl mode" about 14 months ago. But now, I've reached a point where even though I am still constantly worried about whether I'm "passing" or not, I don't let it stop me from going out anymore even if I am feeling like there's no way in hell I'm passing that day. My base appearance is still sort of in "gender contradiction" mode, so because I really don't have a choice, the options are either to go out in "girl mode" and get stared at by a few people or go out in "guy mode" and get stared at by a few people. So I really just don't care anymore. When there's no out, no way to escape the stares no matter what, it stops being something that interferes with your life so much.
When you think about it, it's other people's problem, not yours. You're just doing what makes you happy. It's others' narrow-minded notions of binary gender that is the problem.