[Question] What are the pros and cons of seeking a formal diagnosis of autism?

I suspect myself to be borderline autistic, and while I can function in society, I might have a diagnosable condition. (More details below.) Is it in my interest to seek diagnosis? I believe many viewers and commenters on this site are in similar situations, so I hope that this question will be useful to others and not just to me. I’ve listed some of the pros and cons I can think of below, but I’m probably missing some.

Pros:

A formal diagnosis means you can ask for special consideration and usually get it, even if you don’t strictly need it. For example, accommodations to make a work environment less distracting. If I’m undiagnosed and just find things irritating, I have to put up with them. (Not so relevant for me, but students may be able to get more time on exams which is a big advantage.)

Many people seem to find a formal diagnosis helpful for understanding themselves (are there advantages over a self-diagnosis?) and for explaining themselves to others.

Cons:

Are there circumstances where having a formal diagnosis could make me more vulnerable to being stigmatized or labeled? For example, if I were to suffer a different medical condition and be admitted to hospital, will the doctors/​nurses treat me like an idiot because I have ‘autistic’ on my medical records? Relatedly, if I get dementia when I’m old, will I be infantilised and treated as lacking capacity at a much earlier stage than non-autistics because of the pre-existing autism diagnosis?

I could just explain to people that eg I don’t like last-minute changes of plans. Is there an advantage to explaining to other people that it’s because I’m autistic, rather than just saying it’s part of my personality?

Is it socially responsible to seek diagnosis for borderline cases? There’s an argument that the modern world is far too quick to pathologise behaviour that is only slightly different from normal. Should I avoid contributing to this trend?

Personal details: I have difficulty making friends and have gone through periods of my life where I had no friends. I was bullied at school for being obviously different from other children. I think analytically and respond to ideas more than personalities. I found LessWrong’s explanation of non-autistic behaviour to be very helpful: what was sometimes baffling is now explained by status-seeking and signalling. I personally seem to lack most of the status-regulation emotions and the mental architecture that makes most people engage in this behaviour automatically. On the other hand, I don’t have stimming behaviour and don’t display special interests to an autistic level. I had no developmental delays and have a good job. If I am autistic, I would be labelled high-functioning.

NB: I personally live in the UK, so British law and culture are relevant. I would like this thread to be useful to others too, so please post about the situation in the US or other countries, just make sure you say which you’re talking about.