I feel for everyone in this situation. My teen DD had this problem between ages 15-16. She had a best friend at school who started to get in with a crowd outside of school my DD didn't like - bit of drinking, just hanging around the shops acting stupid.
My DD again was quite mature for her age and just didn't get the drinkin to get drunk, getting off with loads of boys thing and rebelled against her. Her best friend then got a boyfriend and had a major pregnancy scare despite DD telling her she was acting in a crazy way - the advice didn't go down well and they had a fall out- since sort of patched up and they still catch up from time to time.
She had other friends who were really nice to her at school but she just wasn't seen as "cool"- they all seemed to get invited to the older kids parties etc and she regularly suffered seeing all the fun stuff going on on Facebook-pictures of parties etc she hadn't been invited to.
Initially it really hurt her but then she made one really good friend who unfortunately moved overseas, but it was meeting that person by chance who she really clicked with which made her see that some people really did value her.
She ended up moving school ( in part but not wholly for social reasons) and at her new school ( where she is a boarder) she is so popular- has a lovely boyfriend, a group of lovely supportive friends, a couple of whom came to visit over the summer, etc.
So my message would be, hang in there, do try the external clubs - just to see who is there and meet someone like minded. My DD does also recognise that in not wanting to just follow the herd she did make a sort of rod for her own back- but she came out of it well and learnt something along the way.