Yeah it's funny how people get those so mixed up. Convenient for me, I guess, because I'm half gay and half trans, so the fact that one tends to suggest the other works for me. But it definitely doesn't have to be that way. Who I'm attracted to and who I am are very much separate. I think a lot of why it's such a big deal, for the MtFs, prolly is very much an American thing, that it's hard here for guys who are seen as feminine to get accepted, so to feel accepted among guys they have to hold on to all of their masculine traits possible.
A thing about labels though. So many people are against labels, and I understand where they're coming from, but I'm a real big fan of 'em. I once knew this person, Robbie, who'd come out to their parents as bisexual, pansexual, transgender, and pangender on separate occasions. Or something like that. How confused would YOUR parents be after being told all of those things, including some ideas really foreign to straight cisgender people. I figure, for straight people, I'm willing to take labels (bisexual, transgender/confused) that they're likely to recognize and which fit me at a broad level. The thing is, those labels don't define me; I define them. I won't let myself get trapped by labels. When people ask me if being bi means I'm polyamorous , I correct them that some bisexuals are poly, and some poly-people (what's the plural?) are bi, but the two don't mean the same thing. Same for any other thing people try to attach to who I am.
As for fluidity...I'm curious as to the opinions of the older people. At 22, I can tell you that both my gender and sexuality have small variations, but never long lasting, so that I figure I average out to nearly the middle on both scales. Has anyone found long term trends? Did your orientation or gender identity change at some point in your life? I'm just really curious, because I've heard before how things could be fluid, and I'd like to hear from anyone that's experienced that.