I listen to music that makes me more confident. Also, I somewhat dislike the word passing as it implies that there is some kind of test or something to pass, or that you're passing yourself off as something you're not. I prefer the word "percieved as...", since that is essentially what it is.
I have a lot of trouble understanding how others percieve me. A few days ago, me and two friends (one is a trans guy, the other is a cis girl) went to a café. When the waitress came to collect our plates and cups, she said: "Is it okay if I collect these, girls?". I had to bite my tongue to stop the laughter. My male friend felt hurt by it. My female friend was also a bit sad. To me, it was just an absurd thing that she'd seen us two as girls, it was as if she's said "Hello there, parrots!" to a group of humans, the same kind of bizarre punchline-esque thing to say.