Oh, it's good you are finding faults in yourself, that you doubt yourself. Finding things you don't like is the first step in improving yourself. So cherish every thing you find lacking about you, this are the foundation of the future, better you.
You feel you do not belong in groups? Embrace this feeling, you might find that your strength lies in you doing things alone. Feeling down because happy couples are all around you? First ask yourself - do you feel their love is real or just a fad? And do you wish to be like them? Take a look at yourself from a third perspective and try to imagine how would you act if you'd change things you do not like. Take a good look and ask yourself if this is the person you wish to be. If yes, build on it. If no - re-imagine it. Change the observed environment, change the way you would act, change how you imagine you'd be. You fail, you try again. You learn your entire life. To be at the top of the food chain is no perfection but stagnation, a silent, empty stare into the void that consumes us all. The best know no bottom or top, there is only a circle. To create is to live.
Once you realize just how much you can change yourself by not being restrained by what other (would) think of you, once you start ignoring the borders OTHER people have set, once you stop acknowledging the Great Game of society, once you become a player instead of a pawn...your mind becomes a blank canvas. Your body a block of marble.
And you are the engineer.
Create.