I'm 46 years old and undiagnosed, but getting a professional diagnosis is not a priority for me. My take is that unless you have support needs that requires some sort of bureaucracy to kick in or have concerns about other mental health issues (depression, clinical stress, etc), getting a professional diagnosis is optional.

If you think that getting a diagnosis will bring you some closure, then I think you should investigate that path. But in my opinion the diagnosis should be the means to an end, not the end itself. Closure and self-realization is certainly a valid reason for looking into getting a diagnosis. Getting professional help does not necessarily means getting the diagnosis. You might end up getting screened using tools not quite unlike your online tests, and then after some discussion about what it means to you, decide not to progress further with diagnosis but just continue some sort of therapy session.