some good advice re diet. i fast a lot and it is shocking going back to carbs can make you depressed.  my suggestion is going to sound hokey. many like you repeat negative shit to themselves all the time like it is a mantra. negative self talk is awful. the power of positive thinking sounds new age and bullshit, but it works.  try meditating. at the start it will feel like random shit coming into your head. focus on quieting that and just concentrating on your breath. when clear, picture yourself as the person you want to be - strong confident in a social setting interacting with people. get really detailed, like people laughing at a joke you make. paint the picture you want in your head. keep fine tuning that image, the setting what you are wearing.  then make up repeatable phrases that you can say. people enjoy my company because i am interesting. taylor it to your situation and personality. works best before bed and when you wake up. repeat the phrases a few times a day.  if you want the science read up on conscious and subconscious minds. your conscious mind are the little decisions you make - maybe 10% of your life. the rest is run by your subconscious which is a supercomputer filled with programming. it keeps you alive, runs your heart and bodily functions. many just through life fully run by subconscious - alarm, wake, phone, piss, same breakfast  total autopilot life.  but it also has a lot of bullshit programming in there too. events from childhood, traumas, fear, triggers, etc. when you work yourself up - oh fuck i have to go to christmas dinner, i am going to faint and make a fool of myself, you just added a program that will execute. just re-write the code to your life. the key is putting emotion behind it. when you picture nonaxious you, feel it and imagine it to be real. it takes time, but does work. athletes and business pros do this daily. make it right in your mind first and your body will follow.  good luck anon.
Canada