Trust me when I tell you are not the only girl (or person) who feels this way. We all hate at least one thing about themselves. And when I say that those girls who you think are "drop dead gorgeous" have their hang up about themselves also, they do. Hard to believe, but everyone has things they hate about themselves. You should be proud of who you are and what God has given you. Accept yourself for what you look like. In your eyes, but may be ugly but in someone else's, you are as gorgeous as you think those other girls are. Believe in yourself.
As Scarlet Tears said, you are who you are. Your own person. You should embrace what you have and do what you need to do to make you feel comfortable with who you are. Maybe that will be looking into a mirror and each day telling yourself you are beautiful or putting a bit of make-up. People will love you for who you are.
Your friends and loved ones have accepted you for who you are, so what is stopping you from doing that? You need to have more confidence in yourself and believe that you are beautiful inside and out because you are. And to the people who say you aren't, best thing you are do is not to listen to them. Nobody needs those hurtful comments in their lives.
Best wishes! And remember to believe in yourself :)