Struggling to get my GP to listen - any advice for adult diagnosis request

Hi everyone

All my life I have been a little 'off'', didn't feel like I fit anywhere had crazy little quirks that would make me stand out from the crowd and I had accepted that perhaps I was eccentric. Most of the time it didn't get me down, I had learned how to behave, what to do etc, but with more than a few slip-ups. Anyway, at the beginning of the year, I watched a documentary on Autism and I burst into tears because all of my 'eccentricities' were being described by people with ASD, there wasn't any part of it that I couldn't relate to. So I started to look into it further and realised that my 'struggles/quirks' could well mean that I have ASD, in fact, I am 99.9% sure. After I had accepted this, and felt slightly relieved I couldn't decide whether I wanted to pursue a diagnosis or whether I would be happy enough to be 'self-diagnosed'. A few years ago I was in the hospital and I struggled to communicate with the staff, to the point that I was being given antibiotics I was allergic to, so I decided that it would be useful to get a diagnosis, just as an 'alert' to others that I have ASD, not as a label to define myself. This coupled with the fact that I have no family and few friends, it's just me and my partner, and I could find myself in a vulnerable situation as I get older. A few weeks ago I went to see my GP, I took with me a list of everything, and I struggled to communicate with him, I couldn't find my words and he automatically assumed it was Social Anxiety Disorder - which I know for a fact it is not. As I had assumed he offered me tablets - and at that point, I walked out of the room and decided to write him a letter, accompanying an AQ10 form which scored an 8/10 - I detailed as much as I could without going overboard and I was invited to meet the nurse.

When I went for the appointment with the nurse she was very nice and told me the reason I was meeting with her was that she had more time and I could explain everything to her, which I did. During the appointment, I told her how physically and mentally exhausting social interaction can be, and I often 'crash' afterward. This has been picked up on and the surgery want me to have blood tests to see if my B12 levels are low. Even if they are it doesn't make everything else OK - the inability to socialise 'properly', the sensory overloads, the fear of invaded personal space, the lack of ability to be 'fluid' in my plans, and the meltdowns when I cant cope. I don't know what to do, I have no fight in me, I am exhausted, it has been 36 years that I have been like this, it takes all my strength to go to the appointment and explain - because for some reason I speak and even though in my ears it sounds like English, to everyone else its a different language! I just want to know if I can get a referral, I have trawled the internet for advice and cannot find anything conclusive - so am reaching out to you guys for some advice. I haven't got the resolve to jump through numerous hoops to be 'undiagnosed' with everything else. Should I speak to my local NAS? Can doctors refuse referral requests? What do I do - I just want to run away and not deal with it but my gut tells me I need this diagnosis. Since the self-diagnosis I have felt more confident in dealing with the world around me and it would help if I had an official diagnosis so that if I am in hospital again they would be aware too. Please can someone help and give me some advice? Thank you so much in advance