Hi Gryffin. To answer your question, I imagine people call me a free spirit because I look, walk and talk a little "off-centre", if that makes sense. Like, if everybody is wearing and doing a certain thing, I always seem to be (and not totally intentionally, btw) doing something related, but a bit off on a tangent. A lateral interpretation of the spirit of the times, sort of.
The reason "free spirit" isn't what I would use to describe myself has to do with my own associations with the term. It calls to mind Woodstock and the flower children of the 1960s, with all the free love and bohemian clothes and Mary Jane. Not my scene (obviously, since it was before my time), and not my style. At all. Not even a filtered reflection of it.
But I do understand what other people mean by it -- I act as though the rules don't completely apply to me. And I guess they're right. It's not in subversive way, though. I'm not actively rebellious; I've just always tended to think of myself in one category and everybody else in another. I've got much better as I've got older at seeing myself as part of the big picture, and of taking other people's viewpoints into consideration.