Thank you both for your responses, much appreciated.
Danielle, thank you for sharing some of your own story (sorry to hear how you were treated), yay for your experiences in recent years. I can believe that you 100% pass from your avatar pic. Very feminine and natural) and reassuring me that it's okay to start this kind of thread. I wasn't sure, but I know that I like to ramble and sometimes want to post things that aren't exactly a forum, question-type or big issue post.
It's interesting that you say you had similar photos early on in your own story. The thing is, when I had long hair, I'd fairly regularly get read as FTM transwoman. Kind of like if I played with makeup and if you stuck a wig on me, I don't entirely pass as a cis-woman, which felt a bit strange to me. I was struck by a documentary I watched about transmen in which one lad looked at an old photo of him as female and they said "it looks like you, with a wig" "man in drag". I could relate, as if the more I tried to look very feminine, the more wrong I looked.
I still looked okay, nice enough, but there was something that little bit "off" about me. I was also approached on FB by a couple of transwomen and by a local transwomen group! Erm... very kind of you ladies and glad you have your group but...no?!
In other situations, probably my manner didn't help either. Not that I am all that manly in my demeanour or voice, but again something subtle, like a woman with overt stereotypical Aspergers, not quite fitting the female social code. I studied (at that time) male-dominated subjects and spent most of my time around boys/men and fit in quite well... always as a 'good friend' and never as 'girl I'd potentially date'. I think some of my ways of talking, opinions and sense of humour sat better with men than women. But then again I'm not convinced such things are innately gendered when we have a culture in which we are saturated with expectations pretty much from birth.
Hehe I'm 5'4" too! I had my growth spurt (and puberty) early and so was one of the tallest in my year for a while, before ending up on the shorter side!
Luckily in terms of gender dysphoria, I had a good cis-male friend a while back who was 5'3" and he was as blokey as it gets, so I have an internal model of "short male".
autumn08 - Thanks for the compliment

I'm learning the genetics stuff myself, still learning. My GP is not very approachable about things (complex and loooong medical history both physical and medical, combined with NHS time restraints and a resistance to anything done privately)
From what I can tell, XXY doesn't require any kind of treatment usually (other than for some males, gynacomastia) but really not much out there about female phenotypes - a couple of cases in research studies which mostly seem to end up with people shrugging their shoulders about the whole thing.
I cannot know, but it made me wonder if that was something to do with my ungirliness. Obviously not anatomically, but the Y chromosome supposedly acts elsewhere and in other ways too. Who knows?
It does make me wonder if I have some sort of AR as well, and I wonder how that might affect things if I ever chose to, was able, was allowed to take T. Could render it pointless.
I haven't felt comfortable with my gender expression so far. It feels like I have been trying to be something that isn't natural for me, somehow fake, hard work and imposed by social pressures.
I'm reasonably comfortable presenting fairly non-binary/androgynous because it's easier and more natural, although cause confusion in people sometimes.
I do have intense dysphoria about my chest though. I have hated having breasts ever since they appeared and wanted top surgery since I was a teenager (but never associated that with being in any way trans, just as a personal quirk/issue and weirdness.) They felt like some alien blobs put onto my body that didn't belong there and were unwanted. Yeah, my chest causes me distress.
Also never liked having women's genitals much, especially having a uterus. Does that sound odd? Again, things I didn't want but were arbitrarily there. Not sure I want male genitals either though but that could be partly because I've not thought about it much before and is alien to me in a different way because I can't imagine what would be like to have them. I have tried packing at home in private a few times. It's definitely interesting, different, and I kind of like it

but the real thing would be quite different I'd imagine. Also not sure about facial hair. It would be a basic for "passing" but not sure how I'd react to having my face look that different, and feels more forced than naturally wanted. Also wonder what it'd be like on my pale face. Maybe stubble or that shadow would work.
I feel like I can't make an definite assertion or decision largely because I feel I could never pass, and my anxiety (esp social anxiety) would make it near impossible to take that first leap in terms of bathrooms and changing rooms. I'm anxious enough around normal social situations. Enhanced by the whole 1? 2? year RLE prerequisite where I'd have to do those sorts of things whilst still clearly not passing. That terrifies me. I can't see how 40 year old male with no facial hair and baby soft skin could be read as anything but trans and lead to threatening situations. I've had more than enough trauma in my life. Also the suspicion that given my mental health history and stuff, a GP would be very unlikely to take me seriously or refer or prescribe.
That's the fear-based baggage I have to work through mentally and emotionally to allow me the freedom to know what I am and what I want.
I'm tempted to find a private counsellor if/when I can afford it to talk that through (though again, fear, I know how much therapists want/tend to jump on issues from my past and aside from having done a ton of therapy on that before, some things it does me no good to keep rehashing. I've never talked about the gender issues because other things and my overall mental health were much more urgent.)