Self-diagnosing is valid.
No, I don’t mean that just anyone can decide they have a disorder. But if you have done in-depth research on an issue, or an educated, non-biased professional gets enough information to say you might have a disorder, if symptoms line up, if you hit the required points in the DSM, I think it’s valid to say that you looked at the facts and likely have a disorder.
I.e., I’m autistic. This is self-diagnosed, currently. Why? Both my biological brothers have characteristics of/have been diagnosed with autism. My dad has strong symptoms from what I have seen. I stim. I have sensory issues. I have meltdowns when I get too stressed out. I have special interests. I have echolalia. My therapists, psychiatrists, and counsellors all agree I have strong symptoms. However, I am not yet diagnosed, because I’m a POC biologically female teenager and places who do screenings for autism are biased, so they keep rejecting even letting me go take the screening test. We’ve been trying to get me screened for a year. But all the evidence points toward myself being autistic, and so I use the label.
If you have the research, truly in-depth, in particular with stigmatized disorders like DID or ASPD, not only is self-diagnosing valid, but it can also be safer. I.e., people with ASPD can be locked out of certain professions. Getting an official diagnosis could take away a dream. Many people with these disorders, once they learn about it, can get abused by their therapists, being told they’re making up symptoms or that they’re too well-adjusted to have that disorder.
No one should be forced to get an official diagnosis, especially if it could be detrimental to them.