Most Helpful Guy
By adults, do you mean like parents, aunts and grandparents? Like it doesn't really count. They Do mean it, but it's like their job to do so, you'll always be beautiful to them.
And by friends, do you mean other girls? Don't mind them! They see you as competition, of course they wanna bring you down. Girls are mean at those ages.
I know I didn't answer your question, so you better just put a photo on How do I look section.
Good luck and don't mind whoever says you're not pretty. That's not how you should be defined.
Most Helpful Girl
Your friends are being complete assholes. Instead of giving you advice on how to better yourself, they call you ugly. Are you overweight? If yes, then try to lose weight by exercising and eating healthy.
Does your skin have minor issues? If yes, then try to get rid of them applying various products.
Does your current haircut/hairstyle not suit your face? Change it.
There are plenty youtube tutorials you can check online.