My process was quite easy actually. A friend mentioned to me I might look into whether or not I was autistic. I was in disbelief at first, but once I learned about high masking autistics and what the constellation of symptoms were, and after I scored off the charts on all the online tests including the CAT-Q (which measures masking techniques), I was determined to go find a psychiatrist to corroborate what I already knew. She did about an hour's worth of testing, interviewed me some, and was able to give me the diagnosis on the spot. She ruled out the Cluster B's and OCD and ADHD. It was such a relief like I said. I see color so brightly, I am so sensitive to light, I feel my emotions so strongly but they confuse me so much...now I have an answer as to why.
I hope your diagnosis is this easy and relieving for you too.