Well, a shame that this thread went down hill, sorry OP! Perhaps those wishing to discuss bimodality versus binary would kindly stop replying here and have a no-doubt riveting discussion in another thread, so that @VanishingVision can have their thread back!
To answer @BonfireLady, I'll explain the way I conceptualise myself and transition. I'm happy for anyone to disagree, this is just the way I conceptualise it.
My feeling is that, as a sexed species, our brains have certain sex-based pathways and predispositions. These would have helped guide our ancient ancestors to reproduce, seek good partners, etc. The most obvious of these sex-based brain functions is sexual attraction: males are typically sexually attracted to females, and vice versa. But clearly this sex-based difference is not so clear cut; some people experience same sex attraction, or both, or neither. I don't claim why this happens, I suspect it is developmental in the womb, but it doesn't matter even if it forms later.
I don't see any reason why other aspects of behaviour couldn't also be informed by sex-based brain differences. For example, it stands to reason to me that there must be some circuitry in the brain that controls the desire of making oneself presentable for a partner. We know many species of animals go to great lengths to make themselves look attractive to a mate, and humans certainly seem to do it too. Now what constitutes attractive does vary with culture etc, but I suspect there is some degree to which children's brains automatically observe what constitutes attractiveness for their sex, and then may try to replicate this. Just like sexuality, I think this varies considerably, some people care deeply about their attractiveness, some people not much. I don't see why this circuitry couldn't also 'miss-fire' or 'miss-specialise' and end up causing someone to try to be an attractive member of the opposite sex.
For me this is probably what gender dysphoria actually is. One or more brain features, like those that I describe, that can miss-fire and end up having the opposite-sex effect (or some mix). My experience with talking to different trans people makes me think there are a few such circuits, not just one, so any given trans person will have a mix of sex-typical and sex-atypical circuits, resulting in different presentations of GD. So in my case I'd say some sort of 'proprioception' circuit is wrong, giving me the real feeling that I shouldn't have male anatomy as I do. I also feel very strongly that I'd want to be considered by my partner to be his wife or girlfriend rather than his husband or boyfriend, which is about the only social aspect that really bothers me. Fortunately, getting one person to agree is much easier than getting all of society to change! Also I guess I've found my sense of style leans heavily to being very feminine in presentation, but that's a less strong desire for me, so maybe that circuit is only somewhat anomalous for me.
This is all just my crazy theory, like I say, feel free to shoot it to pieces, but it's how I think about it!
So with that in mind, I just see myself as a male with several mis-firing circuits in my brain. Pragmatically, I can relieve the stress they give me by 'giving in' and adopting a 'woman' role in society, even though I know I'm male. I also highly doubt ALL my brain circuits are sex-atypical, I'm sure most will probably be sex-typical, so it's a balanced trade-off for me of how 'trans' I think I am. Now whether what I've described counts as believing in 'gendered souls' or 'gender identity' is up to you, but that's how I see it myself 😅
Regarding some of your later points, the difference for me is in outcomes: transition does genuinely seem to help some people, I argue it has helped me so far. To my knowledge, amputating limbs of BIID doesn't ultimately bring positive outcomes. I transitioned because I honestly think it is a good balance given the way my brain is.