I am also worried about my voice, probably more than anything else about eventually trying to pass, and I have not done more than a little bit of toying around. Even that was a month or so back (I've been busy with other things). So I can't speak from experience post-transition or having conquered the voice challenge, but I have spent a lot of time thinking about this.
Nothing is wrong with you. Your voice is a major part of your identity. People recognize each other by voice, you have been hearing your own voice every day for as long as you can remember, and most likely you never thought about how to make it sound like it does. Most people just talk how they talk, and whatever that sound is, is them. It's really unnatural to set about changing that, and it digs at the core of your self identity. It is entirely reasonable to find it difficult to change this!
The identity/psychology thing is tough. I have very mixed feelings about it, both for myself and for others who identify me with my current voice. But I think I will end up changing it. It will be weird for a while, but eventually I am confident that I and others will adapt. It's happened before---I had a different voice when I was 10, I sounded funny for a while, and now I barely remember the old voice. I don't think the fact that I'm making a conscious choice to change my voice makes any difference.
The fact that most of us just speak in the way that developed without conscious effort, voice training and practice is really alien. We don't think about controlling the muscles that we use, we just talk and something comes out. Our brains haven't bothered mapping how signals to various muscles translate into movements or sounds, nor have they worked out how those movements translate into sensations. So it's like trying to write with your foot, blindfolded. You know what you are trying to do, but no matter how much you think about it, you can't just will your body into producing that result
My daughter is learning to talk right now. It's cute because baby, but ignoring her age, objectively she is really terrible at it! You ask her to say "peanut" and she says "eenorff." That's almost entirely wrong! But she doesn't get frustrated, she's proud of her achievement. It had the right rhythm and the vowels were close. And she'd be really happy if you asked her to say it again 300 times in a row. Her body has to learn, from no experience, what it feels like to make sounds, what sounds that she hears are her own voice, and how to use that to reproduce a word someone else said.
You're better off in some ways, because you have the rules down, but there's no way around the practice to close the loop between muscle, sound, and sensation. That's going to take time and effort, and until you get fairly good at it, the results will not often be pretty. I think it's probably like learning to play a musical instrument. My experience there is that you have to practice consistently, and you have to practice properly. It's neither essential nor possible to play something correctly the first time you try it. If you try to learn a piece by starting at the first measure and playing note by note, getting frustrated and starting over each time you make a mistake, you will never get anywhere. You do the best you can each day, and you concentrate on fixing one problem at a time. After a while, things start to click, and even though you didn't stress yourself out seeking perfection, you found your way inch by inch to the goal.
