It seems to me like OP is just coming of age and is beginning to realize the world isn't all fun and games and actually kinda sucks for the most part. However the whole 'I don't feel happy no matter what I do' sounds like a symptom of clinical depression. Not depression as in the tumblr-tier "boohoo im so sad + hate people", I mean depression as in you are showing real symptoms which result in a lack of confidence and motivation.
When you're feeling this way it's important to not focus on the past/your flaws but rather what you can do in your current situation. It's all about small victories. Feeling awkward around people? Spark up a conversation with someone, if it goes well, it'll boost your confidence. Also remember that you are actually 12(?) years old and from experience I can tell you in the next 6 years, everything is going to change so much it's actually crazy. Things will probably be the worst around the age of 15 but after that you'll begin to settle more comfortably into your skin and your environment. Just make the most of your young innocence while you can because with age comes responsibility.
