I understand what you're saying about co-opting someone else's identity because it's "cool," and I do think that happens sometimes, but your struggle is obviously sincere. And the person who decided to "teach" you how to be genderqueer would still have been an asshole if they really were genderqueer. Belonging to a group doesn't entitle you to police other people who belong to that group. If you find a particular category helpful in understanding or explaining yourself, and you're not going around telling other people for whom that category means other things that they're doing it wrong, I think you're okay.