I'm female, older, and self-diagnosed. I've considered getting an assessment but it's expensive, and as others have noted diagnosis is difficult for older people especially women. If it came back negative, I'd be left thinking 1) was it an accurate assessment, and 2) what now - I guess I am just a freak. I've read a ton, taken the online assessments, and I feel fairly confident in my self-diagnosis.
For me this is it in a nutshell. I'm tired of hearing "you just need to join more groups", "it just takes practice to get better at social interactions". Sorry no, I'm not wired that way, never will be, and the older I get the more it becomes clear that 1) I can't fix this, and 2) life is not worth living if you don't have connections with other people.