"How a word is used" is not the same as "how you personally use a word"
Individuals don't get to determine the meaning of words, and that's what you're trying to do by insisting that "terrorist" has some kind of special meaning beyond "enemy of the state". Words are defined by law and history and society and usage, not individuals.
Legally, a "terrorist" can only be a "designated enemy of the state"
Historically, "terrorist" has always just meant "designated enemy of the state"
Socially, a "terrorist" is just used to refer to "designated enemy of the state"
And, in common usage, "terrorist" just means "designated enemy of the state"
You're trying to insist on some more concrete meaning beyond this, and it's just not real. It's a useless word for us.