This post is not, strictly speaking (no pun intended), about transsexualism as a congenital disorder, but there needed to be a follow-up to the post called Resolution. For a woman born with transsexualism, there is one thing that makes being a woman not quite as easy as just being herself.
When you change sex after puberty, what testosterone did to your vocal cords is not undone. Testosterone made them thicker. That can't be wished away. Despite the old joke, castration will not make you sing soprano, unless it's done when you are still singing soprano.
Part of being yourself is to speak like yourself. And most women speak like women. Just as you get help from an electrologist because you can't permanently remove your own hair, you might need to get help from a professional who knows how to help you find a natural voice that fits who you really are. There are also less expensive and even free resources available.
As anyone who has worked on their voice knows, it's not just about pitch. In fact, it's not primarily about pitch, although it's probably good to avoid the dips in pitch on some vowels that are typical of a male voice. It's more about changing the place of resonance than elevating pitch. It's also about letting yourself be more expressive. Finding a new natural voice is difficult for most, but it can be done. And if it just came to you, consider yourself lucky.
Your voice is an expression of yourself. It is part of the impression you make on people, and in situations where others can't see you, it's the only impression. If you want people to do a double-take every time you speak and call you "sir" on the phone, that's your business. But I imagine most women, when they speak, would prefer that people hear a woman. And prefer to hear a woman in their own ears as well.