OP here, just wanted to say thank you so much to everyone who posted. I tried to respond to everyone's comments/questions individually, but HN was saying I was posting too fast after posting just one comment.
In response to some questions/comments:
I have read George Leonard's "Mastery" and it is extraordinarily relevant in this case. I'm reassured to hear from everyone posting here that if I put in the work, I'll get to where I want to be (eventually).
Re code samples: this isn't my regular account, so I'm not really comfortable sharing in the context of this post. I wouldn't want potential employers and people I'm working with now to see that I'm having these kind of doubts.
I'll try to stop being so hard on myself, and stop comparing myself to others. My only competition is myself.
Anyhow, this community never ceases to amaze and inspire me. So, again, THANK YOU! I'll be coming here for inspiration when I need it.