I completely agree with you. As an introverted person, I love how others are so confident, but I have a hard time living in my skin because, like you, I am a writer/artist and I do not feel validated in real time. For example, where I work I am a server in a restaurant and it is very hard for me, because I am so receptive to so many avenues of communication and energy that I am often overstimulated.
As a left-handed person, too, the computer was eventually set-up to be used by a left-handed person, and it showed me and my colleagues how befuddling using it was when it was for a right-handed person. I had to use this computer for 27 years and it made me feel like an idiot. Nothing was ever where I intuitively thought it should be and it made me question myself. Now, when people use the computer with my number, they get to see what I see, and as right-handed people, it frustrates them.
For the longest time, I would be so affected by people's energy that I couldn't write clearly, which made putting in their orders extremely difficult. I often would have to go back and ask them what I might have meant when I wrote a particular item.
As a photographer, as a composer/producer of music, as a singer, as a graphic designer, as a painter, as a remodeler, as a poet, as a novelist, as a short story writer, as a reviewer of art, movies, and books, etc., in everything I do, I question myself because I simply have not made a living doing the things I am very good at. I jump around a lot and that's perhaps undermined my money-making capacity and inevitably my confidence.
So, I am envious of confident people.
My ex-wife, for example, had master's degrees in Economics and Spanish Literature by the time she was 23. It took me until I graduated with a degree in Speech before I began writing in a manner that seemed to coalesce my sense of writing. Then, I wrote for the University newspaper anyway I wanted and it was an explosion of happiness and productivity. One person said that I should be writing for Rolling Stone.
At work, I was told by the Director of the White Collar Crime Unit that I should submit a paper I wrote to a Law Journal. I didn't believe him. Looking back, I should have done that.
On Friday night, I was told by a group of New York Times Photographers, "If you have a Master’s in Photography, what are you doing here?" I was taking their orders for food and drink. It hurts being me, but not really. I am successful on my own terms.
