After giving this whole subject some considerable thought, purely out of curiosity and a wish to make sense of it, I currently have this train of thoughts:

Although I do believe that there is a continuum from 'totally male' to 'totally female' and that the in-womb hormonal balance plays a big part in defining where we are on that scale, there must be more to it than that. As AbiDrew said, she prefers to think of it as a cloud and thats a pretty good way of putting it, I've said '3-D' myself, in the past, but even that is too rigid.

Soooo, I suspect that one/some of these other factors may be what tips an individual over the edge into being an all-the-way TS, even if the in-womb environment is what starts it. The basic logic behind this thought is that there does appear to be three distinct sets of effect from males taking female hormones, in whatever form: (a) Fully male males, get really upset, screwed up and generally react badly.(b) Some (the majority of us here) get a general sense of well being, reduction in stress, etc, and also a surprising reduction in the need to cross-dress and other female type interests. (c ) Some suddenly feel liberated, even more female and realise that they do indeed want to go all the way.
(a) Is logical and what we might expect and we can ignore that.
(b) Makes sense for the simple 'inbetweenies' who's brains expect a level of femaleness that their male bodies can't provide
(c ) There must be some other factor(s) involved to bring this fairly extreme need, to the surface, although I have no idea what they may be.

So, I don't think the term 'brain re-wiring' is correct. Re-wiring implies physically changing what is there now into something different. What we are actually doing is probably more a case of re-balancing - think of steering wheel judder that magically disappears if you get the wheels re-balanced and the whole car suddenly feels smoother and more comfortable. Maybe for TS's, they actually need not just a re-balance but a whole new set of tyres?

wow, talk about a nail hit squarely on the head.

I doubt it could be described better.

Wow, what a deep thread. xD I do really like the term re-balancing, it makes a lot of sense.

I'm not sure that I would actually describe myself as an introvert but I'm certainly more towards introvert than extrovert. However the female side of me, back in my active CD days, was very flamboyant and I was once asked if I was French because I used my arms so much!
I also wouldn't describe myself as a loner but I'm not happy in crowds and I'm not good at small talk, although I do get lonely if I am actually on my own for any length of time.

You just described the opposite of me. I'm definitely more of an introvert than an extrovert, too, although when I'm just hanging out as "one of the guys", I feel a lot more social and a lot less awkward. But when I'm hanging out with a bunch of girl friends or I get hit on, I suddenly feel more vulnerable and tend to shell-up a little bit. :/ It's weird to really think about. I'm not really sure how my own brain works half the time. It's like my feminine side super-activates my anxiety.

So far with my NBE, I haven't experienced any type of real "re-balancing". But I also haven't been raising my hormone levels too high, so when I start PM, there's still a chance that some re-balancing will occur. I'm actually really curious to see what happens, and while part of me really hopes that getting my hormone levels to where they ideally should be is all I need to feel like the woman I am, there's still a part of me clinging to the dream of being male. I know there's nothing I can do to really make myself male, and everything I'm doing is a desperate attempt to just fit in as a female. If the PM really can re-balance my brain, then that'll just make things that much easier for myself. Although if it hasn't happened so far, I'm beginning to doubt that my brain will ever start thinking on that one path...

Sometimes I really wish things could be black and white simple for things like this...

Hi everyone, hi Doll. I know exactly what you are talking about when you said that you shell up when a girl hits on you.

also, everything else in this thread makes so much sense

I'm definitely more of an introvert than an extrovert, too, although when I'm just hanging out as "one of the guys", I feel a lot more social and a lot less awkward. But when I'm hanging out with a bunch of girl friends or I get hit on, I suddenly feel more vulnerable and tend to shell-up a little bit. :/ It's weird to really think about. I'm not really sure how my own brain works half the time. It's like my feminine side super-activates my anxiety.

How you described yourself sounds like the opposite of me. I'm also an introvert, but my feminine side as it could be called, has quite the opposite effect on me in regards to anxiety. Maybe that's the way it has to be for me. I think it would've been far more difficult for me to pursue activities like crossdressing and NBE if such activities made me feel more anxious instead of less. If anything, I think my feminine side makes me feel more confident with myself and that subsequently decreases my anxiety.

As far as shelling up when a girl hits on me, I don't think that's an issue for me as I tend to oblivious when it comes to flirting. If I did pick up on a girl flirting with me, I would probably blush, smile and act coy.