Glad that you introduced yourself.
Regarding:
“Alt-right” has been a confusing and often changing label, and a lot of people have been confused about the distinction, including some Trump supporters at times. I apologize for contributing to that confusion.
You're right about it changing. When the "Trump train" started rolling, alt-right was a catchall term that included White Nationalists, the New Right, the Dissident Right, the populist Right and prolly others. It's certainly not your fault that you used the term in that way, as everyone else was at the - including self-identified alt-rightists.
The term narrowed to mean White Nationalism (more or less) after the so-called Heilgate incident at Richard Spencer's 2016 NPI conference on November 21st of that year. But there was a lag effect: some of the other folks stuck with alt-right because they saw Heilgate as a spoof or a troll.