TL;DR: I'm a sociopath and it took me 30 years to learn what true empathy is because the coping mechanisms are strong.

The label thing is tricky, so depending on your preferences you could call me a "pro-social sociopath" or perhaps a person with a "sociopathic personality style" or alternatively you could describe me as high on the Machiavellian aspect of the dark triad. The Neo Pi-R Big Five would describe me as having a "cold blooded" conflict style, with a bland emotional life and disagreeable tendencies. Basically, it's easy for me to be a dick and I have to take a lot of precautions not to.

To answer the call of OP's question, I always felt something was wrong, but I didn't have the knowledge or context to tell what it was. It's like when you're finally grown and you have an ill fitting item of clothing (like shoes, bras, whatever it is) but since you've been growing into your clothes your whole life, you don't know how things are supposed to fit a settled body. I knew there was this vital thing I was missing, I knew I was terrible at knowing what to do when people are sad, I knew I viewed sadness as a problem to be solved, not an emotion to be shared. I felt isolated, cut off from others, anxious because I wasn't sure if I was doing the right thing because I didn't have access to the empathetic emotional clues people get from each other in conversation. Instead, I have a highly advanced "theory of mind" form of cognitive empathy where I can mentally reverse-engineer people's lives without conscious effort and project their interests and fears based upon cold-reading and information I gather as I observe/converse with them. The problem with this particular form of empathy is that it is just good enough a substitute for having both that a person can get by without having to learn and change. I thought I was very empathetic, because I could predict with great accuracy what other people where feeling or would feel after exposure to whatever stimuli. What I didn't understand is that empathy has an element of "compassion" which means "to suffer along-side." I cannot imagine wanting to share someone else's negative emotions. I don't really ever share people's emotions, outside perhaps the feeling of being in a crowd during some corporate activity (concert, sporting event) then I can feel an energy. It makes me kinda ham-handed at some of the more delicate emotional situations in life. I'm direct (like a bulldozer), assertive, and have trouble with unspoken rules/boundaries/expectations. I can't be friends with some people because they won't understand me and I will hurt them inadvertently. I am lucky to have people that love me and are patient with me. I know I can be hard to live with. It's kinda like a curse where emotional destruction follows in my wake regardless of my intentions unless I am constantly vigilant. It makes me sad that I hurt other people when I don't mean to and I try really hard not to and to be as kind as I can be to build up some goodwill for when I fuck up eventually.