Hi. I'm not sure how open you are to alternative, new agey stuff, but some of what you have said resonates with me. I also had 4 octaves, but lack of practice, age and being a smoker has taken a lot of my top range. I learned to be a yeller, off my Dad, and I think this is how I ended up with a big singing voice, also not needing a microphone in many situations. One day I was so angry at something, I yelled so hard (not just loud but hard) that I actually peed myself, significantly. I knew I had to do something about the way I expressed myself. I was out of control. I grew up in the death throes of the "children are to be seen and not heard" victorian attitudes. I was often told I was an 'upstart' for speaking intelligently to my Mother, not so much my Father. Although many of my parents' friends enjoyed talking to me because I was intelligent. I was also treated as 'lesser' in many ways because I am a girl. So needless today, I saw yelling working for my Father, to be able to express many of his needs and wants, so I adopted it. I had to do years of work on myself to learn to control, not just the yelling, but my voice which carries easily, even when I'm not yelling. I stopped singing a few years ago and started public speaking instead. It was as a political activist and found I was even more satisfied by it. But I digress.
Having a naturally strong set of vocal cords, intelligence and creativity means you become very reliant on vocal expression, as you pointed out. In your lifestyle, being Mother to 2 children with autism, (Kudos multiplied by 100 to you) I imagine your needs come second a hell of a lot. And your voice, as your main avenue for self expression is reflecting this, in a holistic way. I'm having trouble explaining this properly, but I'm knee deep in it now, so I will keep going.
If you have heard of Louise Hay, have a bit of a read of what she says about it and maybe try some her recommended affirmations. When I am in a toxic surrounding and not able to express myself vocally, in various ways (not yelling anymore... not much anyway) I find I get a sore throat and ear problems. I think it's my psyche telling me to stop listening and talking to toxic people. So I use Louise Hay's techniques until I can get out of the situation. Not that your situation is toxic, but it is challenging for different reasons. I'm sure there is a physical cause for your symptoms, but the reason I asked if you are open to new agey stuff, is that tackling these mysterious maladies from both physical and psychological / emotional angles is often effective.
P.S. I love the vibrato in your voice.