Kuwisdelu, what you're talking about with the shifting preferences based on how you think of yourself is actually reasonably common for bi-gender people.
And even for some transsexual people, too. And for a while when I thought I was bi-gender, I couldn't figure out how to describe my orientation either. Yours definitely sounds like "straightish and bi-gender" to me.
Early in transition, I realized that thinking of myself as female instead of male made me _slightly_ curious about the idea of sex with a man, and made me much more comfortable with the idea of sex with a woman, so I think in my case, my self-perception affected my feelings on sex. Transition also sorta changed the sort of traits I find attractive, and some other stuff. But my brief experimental fantasies about guys never had me in a submissive role, so I don't think there's any reason to speculate that yours are about submission either.
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I'm not a big fan of the assumed butch/femme dichotomy in lesbian relationships, and most lesbians I know are kinda uncomfortable with it too. Butch/femme is _totally awesome_ for people who fit into it, but I'd say that of the majority of the lesbian couples I know personally, including the one I'm half of, it's not really a thing. I know that in some regions, it's a big cultural thing, but I don't think it's an inherent trait or anything. Really, it's too hard to prove that "masculine" or "feminine" objectively exist, much less that having one of each is inherent to most relationships.
While I was in Norway, a well-meaning but clueless cousin of my girlfriend declared that all relationships had a masculine and feminine energy and asked which of us was which. *sighs* It was kinda awkward, and she wasn't even talking about sex. I don't think either of us can be solidly categorized as either. We like to experiment with gender roles a little at times, but just for fun and in a light-hearted way, and mostly regarding how we present in public. It's not a big deal to us, definitely.
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I also have days when I'd prefer to be completely a-gender, if that's a word.
It totally is. I know two or three people online who identify as such more or less regularly, and others who sometimes feel like that.