Thanks Ryuichi, yeah it helped to vent

That probably was a part of it, looking back after you wrote that. It certainly did bother me in the question being out of the blue and unnecessary and not making a difference, but now I think more yeah I probably dislike those questions or implications because I am still not quite sure what/where I am myself so it's like being asked by some random stranger to pin a definite label on myself before I am ready to.
I find charity shops a bit weird in some ways anyway - the (volunteer) staff. You get those who are friendly and helpful, those whose abilities aren't quite up to the task and after queuing for 15 minutes while they try to serve the person in front I tend to get impatient and leave (partly due to my own inabilities, overload, anxiety, joint pain from standing still). Then you get the frosty old biddies. Then the apathetic ones who have clearly been sent there by the Jobcentre. My most uncomfortable are the teenagers who are either Jobcentre or work experience I suspect, because they don't seem to want to be there, who sit at the counter in pairs playing on their phones, whispering to each other and giggling which just makes me feel uncomfortable.
I love charity shops in general but there are some downsides to having voluntary staff.
Contrasted with my experience in a high street shop the other week.
They'd rearrange the shop again so women's was on one floor and men's and kids' on another. So with my armful of men's jeans and t-shirts I walked up to the changing rooms and had a momentary "Oh bollocks, which do I go in?" and went for women's. The young lass working there did that sort of smile that I often get, went in, tried on. Came out of the changing rooms and she was very enthusiastic and smiley and "Any good?". Not sure what she pegged me as but she didn't make an issue and was perfectly nice.
Also liked that they have both male and female changing rooms on both the male and female floors.
I guess I make it a bit tricky for myself at the moment because I am so inbetween, not trying to or passing as either - leaves me with the question "which changing room would freak people out the least, because I clearly don't totally belong in either of them?"
Overall I think at the moment I'm finding it easier to go with androgynous or non-binary despite my gut feeling being FtM because I know I wouldn't pass at the moment, nor have the confidence to do things like use the male toilets and all that. And I struggle to see myself fitting into current mainstream male stereotypical identities, despite really quite hating having a female body and longing for that to change. I have some mental work to do on that side of things.