How can I help my daughter make friends and stand up for herself?

I need advice. My momma heart hurts. My 11 year old and her best friend of 3 years have been inseparable. We lived in the same apartment complex and they instantly hit it off. Well recently, they bought a house and so they don’t see each other near as often, it’s still frequent. My daughter is more the quiet bookworm, artsy type while her best friend is outgoing and plays every sport out there. They’re complete opposites but get along so well. Until this year. My daughter has a hard time making friends at school and idk how to help. She’s also bullied a lot for her looks and silliness. Her friend does not have the same issue. She has another friend who she has become very close to which is fine. They’re getting more distance between them which I think is sort of a natural thing but my daughter is heartbroken. She’s losing her best friend and I’m unsure of how to help. She’s a sweet girl. Smart, funny and genuine. I might be biased, but I think she’s great! How can I help her make friends and stand up for herself to bullies and learn to love herself? I was the same way so I’m trying my damndest to spare her the life I lived never feeling like I was enough….any advice is appreciated!