I want help knowing if I am my best friends's Best Friend.?

I have this group of friends, I always thought we were really close, but now i'm not so sure. Ok so there is Kelly, Corinne, Bryden, Cody, and Sarah. I always thought we were BFFs! But kelly(who is really shy) didn't invite me to her birthday party, and sarah didn't invite me to her movie night! Kelly often asks me to take pictures of her with all the others, but never asks me to be in them, They have had movie nights without telling me, but i knew. They go out to eat and to movies without even asking/telling me, and I have to find out when they post it on facebook. I feel like they don't think im part of the group. When I tried to have a movie night, nobody came! I'll try to have a party on friday and pray they come, because I thought we were close but now im not so sure. Im invited to some things but not all and only if cody or bryden is hosting the events. and in a facebook picture of a party i wasnt invited to they all had comments saying things like "the gangs all here, finally" IM NOT THERE, I FEEL ABANDONED BY MY FRIENDS HELP! I don't know what to do! I have loads of fun with them and they do too when im around but i need help.