I have learned a lot about myself in the past year. Sharing this perhaps will help others, too. This necessarily longish post covers biological and behavioral aspects of socialization and anxiety. Quite possibly I am overstating or understating a few things, but I'm doing my best with a complex subject.
I have always been a very "sensitive" person, and have been researching the mechanisms underlying that. For one thing, I have to learn how to better handle information coming in from
mirror neurons, particularly when under stress. I seem to have a lot of mirror neurons, or perhaps a few hyperactive ones!
Mirror neurons seem to encourage empathy, learning by example and the kind of mirroring behaviors that engender social connection (and make you darn good at celebrity impersonations at parties, lol). However, the dark side is that you can feel hypersensitive to others' moods and walk on eggshells at the slightest hint of someone in a bad mood, or of apparent judgment, rejection, embarrassment or attack. Unwelcome feelings of obligation and guilt are common. Some bad (but common) social experiences and the usual relentless social messages of "Always play fair and be nice to everyone" accidentally amplified the negative effects, I think.
Being around aggressive, rude, loud people or social groups of vastly different value systems and perspectives often gives rise to a distressing sensation of self-doubt, defensiveness and cognitive dissonance. It can literally feel like being invaded or coerced. Everything is in your face. It can become overwhelming. Rational framing of the situation can disappear. It has possibly been a factor in making me shy, avoidant and non-assertive to an unhealthy degree.
Any idea on how to leverage the strengths of mirror neurons while minimizing the downside of reacting to and being deeply affected by whatever and whomever you're around, like it or not? How can I stop pleasing and appeasing everyone under the sun without losing the natural compassion I find to be a fulfilling natural strength? How does one get a thicker skin without becoming closed off? And how to get past memories of being ridiculed by my peers and so "firmly guided" by adults for such sensitivity since childhood? "You are too sensitive" ... "You are not sensitive enough". WTH??? What about "I am who I am, take it or leave it, I accept it, I no longer let it bother me!" ? But oh it does ...
I apparently absorb social feedback with the same ease with which I breathe air - and it suffuses my brain about as completely. How to filter out the negative? How to set boundaries whose shape is right for me?
Add to the mix the fact that I do tend towards a highly reactive, hypervigilant nervous system and am apparently pretty good at divergent thinking - I can see all sides to an argument and perceive different possibilities - although there's some VERY strong dichotomous (black and white) thinking in there too. Now I begin to grasp WHY socialization can feel so enormously intense and mentally exhausting for me, while also being potentially a source of deep satisfaction. Classic approach-avoidance conflicts right there.
I also have a pretty good memory recall, a vivid imagination, and a tendency to get obsessively focused on potential threats and rewards (that highly active nervous system again). So, negative social feedback triggers memories of the same, imagining a recurrence, and intrusive thoughts about it that are difficult to ignore.
This whole line of reasoning also explains why I am so confident online, but not offline. Online, there is less emotional feedback and no body language to read. Online, I tend to fill in what I CAN'T see or hear with what I WANT to see and hear - validation and positive communal feelings. Unless someone is being blatantly nasty, I "read" all smiles and fuzzy hugs, and that feels fantastic. No wonder I sometimes feel almost addicted to online socialization.
Where I am at right now is fully aware of where I am going wrong socially and with my needlessly pessimistic self-image. I can guess what's happening biologically and psychologically, and I can see that these factors have been a very clear TRIGGER for depression in the past. However, how to FIX this?
My question finally is: how to play to my strengths while minimizing my weaknesses? Perhaps the anxiety angle is where I should start ... or learned negative expectations? Both? How can I feel socially secure, calm, confident and assertive when biology, experience and learned negative expectations so often work against me? I have tried meds several times, by the way, and nothing seems to fully modulate whatever is out of sync. However, self-induced feelings of calm, a few personal victories in a row, and positive social feedback from people of very similar interests and perspectives works absolute wonders with zero side effects.

How to set myself up for more of this when I have
learned to be
habitually tense, passive and socially inhibited, then? How do you get yourself out of a mental habit of lowered expectations, self-defeating discouragement, and seeking external validation because that feels so
natural? I am convinced that this is the key to every issue I struggle with.