Being confused about who you are and wanting to 'fit' in with your friends is a very normal part of being a teenager. Every teenagers has gone through it and it's sometimes referred to as ''growing pains''.
Friends come and go but like in any relatioship, it is also about the balance of '' give and take''.
Apart from searching for people who have the same interests as you, you should also show some form of support and enthusiasm in other people's interests.
I am not asking you to be or act like them, but as a friend, you should show that you care. That way, your friends will do the same for you.
But if thay are deliberately ignoring your comments, then you have every right to go and make new friends elsewhere. That said, have you asked your self why you are unable to sustain friendship with your older peers?
As for your self image, nobody is perfect. Many of us grow up comparing ourselves to the people around us. It is only natural that you won't to be different from everyone else, but there is also the unique personalities that you can adapt and grow into, and, someone with 'unique' personalities that you may eventually grow to hate.
No one likes to be stuck in misery, so overpower your negative thinking. We all have the ability to believe negative things about ourselves but we also have the ability to programme ourselves to believe in positive things.
As you go through your day, focus on the chatter going on inside your head. If you don't like what you're hearing, then stop, and consciously choose a brighter thought.
No one can tell you what you should do with your life. Go with what you're comfortable with and makes you happy. but always remember to be a first versio of your self, instead of a second rate version of somebody else. :