Oh boy, I feel a lot of compassion for you. I can hear your pain. That you are admitting it and not denying and working to feel better is a wonderful sign. Please remember that things change. You are very young and I promise you won't feel this way forever.
You can read self help books and try to change your thinking etc, but our beliefs come from a deeper place, in the belly, and they always overtake how we coach our minds to think. My hope is that you can find a way to look deeper into your core beliefs about yourself or your appearance and see through false beliefs to find comfort in your own skin. We are all inherently worthy of existence and love, but love will evade you, or rather you will unconsciously evade it, as long as you believe you are unloveable. My hope is that you find a way to love yourself just as you are. That will let others then love you too. Hugs