Hi Artemisia,
welcome

(well I'm newbie also, so I don't feel I can be on the welcome committee, but anyways welcome here)

I think I'm XXY, there was never any doubt about my male genitalia but I have most of the other symptoms described for XXY, I had a little breast development, but since I'm very slim if not skinny only me really saw it, tallest of my family, no chest hair, almost no beard until I was like 30, female like wrists and shoulders, never was very strong... difficulties in high school (I quit)... pretty much all that's listed on the Wikipedia page and elsewhere...
also I have it seems a weird type of arthritis, also listed, anyways my knees hurt a lot, or used to.
plus, now, I have had a very fast and quite strong response to low dose HRT. My doctor found a test she can ask for in our public system that is not a karyotype but that she says will show if I have a gene that is doubled. I'm also in the autistic spectrum but I have no official diagnosis for it but it's quite obvious now that I studied autism.
I can tell you that HRT felt as if my whole brain and body was fed for the first time with the right fluids. And my knees don't hurt half as much as before. I feel I'm being repaired
there are many XXY, certainly many who aren't trans, numbers I've seen show one out of 500, one out of 800 or one out of 1000 men birth (they don't seem certain, normal: we're not being checked for that). I'm pretty sure most of them have no genitalia ambiguity, so they actually don't know that they are XXY. so anyways that's many XXYs
I think, well so far in my research, that the consequences of XXY are poorly known. As a matter of fact,if you look at the description of XXY, some pertaining to troubles in teen years seem similar to autism traits. Don't you think?