The author's initial belief that they were somehow special (even if special in a bad way), plus the author's fascination with their own nature (to the extent that they write a blog post about it and how unique their insights are) smacks not of social anxiety but of narcissism.
What is the point of posts like this? So we can all get together and say, "oh boy, I really relate to that"? There doesn't seem to be any insight or useful takeaway from this article besides being relatable for a certain class of people who feel misunderstood.
Most of the things in this article that the author describes as being harrowing cognitive loads, like how long to make eye contact for or hold a handshake, are things that I have heard very socially skilled people talk about in a humorous manner. They have those same reservations and insecurities, the difference is they don't obsess about them. Look around. There is no such thing as "a normal amount of eye contact". Everyone is just winging it.