Great question--good to see some discussion about actually creating music! I'm not an expert on singing but I can share my own experience, having been down a similar path.
Try this--pick up some instrument you've never played before--let's say a violin or a trumpet. Try to play it. That's right, it feels alien. But when you take your favorite instrument--say a guitar--it fits you naturally, both physically and emotionally. You can play it with confidence and expression. When I play guitar I don't have to think about it, I can just go.
Now think of your voice as an instrument. If you don't use it, and haven't learned something about how it works, it's like that unfamiliar instrument. Just because we talk doesn't mean we can sing. These are entirely different things. Only in the past few years have I taken my voice more seriously. I'll never have a great voice, but I can do reasonable stuff that people enjoy within my limited range, and can do credible BGs in my band. It's FUN.
The main things for me were familiarity and confidence. Before I got into singing I sounded like a wounded kitten. I was self conscious and the noise stuck in the back of my throat. My voice would then waver and break up. Ugh.
So I took just a few voice lessons. It was a night school class with a bunch of old farts who wanted to sing Sinatra and Karaoke queens. But it gave me a better understanding of my voice, some tips on stance, projection, articulation, breathing, expression, and a bunch of exercises. I started singing along with some stuff that I liked at home.
Gradually, over time, my voice strengthened. I got more confidence (key). I'm now at the point where I can enjoy singing and fit in comfortably in most situations where some extra vocals are required.
Anyhow, that's my story. Having been where you are, I can only encourage you to keep trying.
