You can be anything you want.No one is limited by other people, only you can limit yourself. Everyone have an awesome potential, it only depends if you want to make the best out of it or just allow others' opinion to bring you down. Being yourself is the best thing ever, its a form of beauty. You can just act, talk, do things that freely express who you are. Because you are who you are and there is only one "you" in this world, even if you have a twin. So what if the you have flaws? So what if you couldn't hit others' expectations? The "you" who you truly are is the one I like best. Its a gift of being special. A true friends accept you the way you are. The things you can do because you are you. And the things you can't do because do because you are you. One day, the someone just for you will come to love you just the way you are. So just be yourself.
People who sees you the way they want and try to control you to become the best and perfect like your parents may tend to bring you down. You might even come to harshly blame yourself for your failures. But you are just you, there are bound to be things that you can't do and flaws that you possesess. If they can't accept you the way you are. Then to me, I will treat it as a loss because they can't see what a gem you are.
Especially when you think of yourself worst too. Everyone is a Kaleidoscope, you can only see your imperfection on the surface but it takes another person to see the jewels and colours that exist within you.
Everyone is special cause you are a gift from God or if you don't believe in God, you are a gift of life. So treasure it. ^^