You are not alone, I think many of us have made similar mistakes. I have also recently made a bad career mistake, I was being promoted to management but without salary increase so I turned it down. Also I lacked confidence in my management abilities. But now I wish I had taken the job, gained confidence, and looked for salary increase by switching the company.

A few suggestions, at least, I am doing these for myself:

* Volunteer to mentor and lead without official title * Read books on management * Improve public speaking skills * Seek mentors and be mentor to others * Focus more on building my network instead learning new of technical skills