Being Me prevents passing.
I have the big hands, I'm too tall with broad shoulders, I've a brow ridge most Neanderthals would respect and a pretty strong chin. My voice needs work, I need to lose weight and I move more like a great ape than a girl. On top of that I'm not even attractive as a man. I don't pass and even with the best makeup, hair, age and situationally appropriate selection of clothing, a nice walk and a smile, I will be seen for what I am, not what I'm attempting to look like.
However, if I do all these things sometimes I can "pass by" before they realize what they have seen. I just need puzzled looks in front of me and the giggles behind me. We have to make a choice and pick an achievable goal if we want to go out in public dressed en femme. If I decided I was going to pass or not be satisfied with the experience, I would never be happy out of the house. I do the best I can and pick a goal that I can achieve and maybe I can raise the bar just a little with each experience. Someday maybe I'll have blank stares in front of me and the puzzled looks behind me. That would work.
If I had a sex change.......
What exactly would change? I would still be the same height, have the same hands and feet and unless I had facial plastic surgery, I would look the same. I probably would be taking hormones and my skin and hair would become more feminine. The difference, in my mind, would be "in my mind". Breasts and new plumbing would make me physically feminine and then I wouldn't have to get past feeling whether I passed or not because if I wanted to do the normal things that every other human does; work, shop, meet people, etc., I would just do it and not care. My presentation as a women would be exactly the same as my female presentation as a crossdresser.
Do whatever you can to make your appearance more feminine but in order to "pass" you need to accept yourself.