Is my friend one of those "impossible" persons?

I have a friend but she isn't really the type of Bff you'd think of. She sometimes acts like she doesn't know anything. Also, she has some sort of power over me that makes me feel bad about myself. She's also creepy and doesn't understand other's privacy! lWhen ever I'm around her though, I have fun and enjoy talking to her! Is this a friend?? As I said above, she acts like she knows what's popular "nowadays" and if I start singing a song from like 3months ago, she'll be like "that's so not in" and give me a look like "what the heck is wrong with you?" but then she'll go and wear like a stupid hair do.she pulls her hair back so the top layer of hair is pulled back in a messy bun while the bottom layer is straight. If I say "I've never seem that hair style before" she gives me that same "what the heck" look.