First of all - there is nothing wrong with you. You are okay. You are not a fuck up, or a spastic. You are doing just fine. I want you to take that in.
And secondly I want to say to you that as human beings, we are a product of our environment - and of our childhoods. If you experienced in your childhood, a lot of fighting, instability at home, verbal or even physical abuse, breakdown of family relationships, feelings of being uncared for or not getting what you need (on any level) from your parents - this impacts on your development and your own senses of identity and sense of self. It can leave you feeling very disassociated from your body and with no real sense of self, recoiling in social situations because they’re painful. When I was in the throws of my CPTSD I wondered if I had autism because I was so disassociated that I when I was socialising, I often couldn’t always tell if someone was joking with me or not, like those kind of social nuances were unreadable to me, so I would just kind of stare at people and try to leave any conversation quickly so I could just get away and be alone, where I felt safe. So, I get that feeling like your defective can be extremely painful and humiliating.
The good news is that you can definitely change this by gaining new knowledge. You can develop and shape yourself as a person and be the type of person you want to be, it just takes you putting in the effort to heal from the hurts of the past and learning about psychology in order to learn coping mechanisms and essentially reparent and reprogram yourself.
Lastly. You are not alone in how you feel - and YOU ARE OKAY - AND YOU ARE DOING JUST FINE. Nothing is wrong with you at all. And what other people think of you does not define who you are at all.