I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)
What you're asking may require practice, rather than just following a new set of guidelines. I have had some formal vocal training, so I can offer some activities that could help.
One important factor in public speaking is breath support. Practice breathing deeply and smoothly, with erect posture and tense abdominal muscles. (Doing this daily can be very refreshing, anyway.)
Practice speaking at various sound levels--softly and loudly--alone (or with a supportive friend) in a room with hard walls and/or floor, so you can hear yourself clearly. Tense the muscles of your throat and soft palate (the back of the roof of your mouth) in different ways to change your voice in ways that may feel and sound unnatural. This should help you gain a better sense of how to use your voice.
When you speak more loudly, does the pitch of your voice go up? Many people do this, because our ears are more sensitive to higher pitches. Try forcing more air through your words to gain volume instead of raising the pitch. In other words, use more air to say the same words by increasing the pressure of your abdominal muscles.
When we speak loudly, we can generally feel a vibration, if we pay attention. When you speak usually, you may find that the sensation is in your throat, or in the far back of your mouth. Force yourself to yawn, but then activate your voice during the yawn (i.e. vocalize the yawn), to place the sensation more in your sinuses and the front of your face (the front of the face is called the masque). This may take some practice, but the most pleasant sonority of most people's voices is achieved by using the face as a resonator.
I hope one or more of those activities can help the sonority and pitch aspects of your voice become more like what you want. I haven't heard your voice, so it may be that I'd think it doesn't need any fixing :) My husband hates his voice, but I think it's great!