How can i come across as more then just her best guy-friend?

my best friend(a girl) and i me are always hanging around in school during lessons when we can, and she is always asking me too sit next to her, ive started hanging around with her group of girl mates and ive become good friends with them the problem is im the only guy in the group and my best friend is seeing more as one of her girlfriends then a possible boyfriend as im the one guy she always confides in and dont get me wrong i like that were so close in that respect but how can i dig my self out of that 'friend zone' hole?