...I'm trying to find out what I'm doing wrong...
We need to know what your interviewers, coworkers, and managers see when they see you.
Things that go through the employer's mind in rough order of precedence:
- Need: Are your skills/knowledge something the company requires?
- Investment: Are your skills worth what the employer pays you?
- Competitive Ability: How does your motivation, speed, and correctness compare to others?
- Competitive Knowledge: How does your domain-specific knowledge compare to others?
- Team Fit: How well do you communicate? Do you get along well with others?
Good companies will try to give employees periodic reviews to let them know which areas they think need improved. Interviewees almost never get this kind of feedback, though.
How have your periodic reviews gone? I don't recall seeing you ever mention them.