I don't understand middle school friends?

this is my first year of middle school and its a lot different then elementary school. in some good ways and in some bad ways. i have made some new friends and i have lost some old friends. during the middle of the school year i was friends with this one girl named daniella. then she started hanging out with the girls that where i guess more popular then me and me and daniella don't really hang out anymore...in fact daniella is mean to me now. i also was friends with 2 other girls named brianna and Ayana. we would sit next to each other at lunch everyday and hang out together after school and one day i went to go sit down with them and they said that they didn't want to sit with me or talk to me anymore. but then later on that day brianna walked over to me and told me that she never meant to hurt my feelings and that she was fine sitting with me but ayana didn't want to sit with me anymore. i also have been friends with a girl named elana since i was born are parents are best friends. we do everything together. we go on vacation together we hang out together we go shopping together and we even go out to eat together. when she stared hanging out with ayana me and Elana became more and more distant. i have a friend named kiara and she spreaded a rumor about me so i stopped being her friend for a week. in that time she went home crying everyday and she tried repedetly to apoligize. i though she was getting what she deserved so i ignored her. then after me and kiara made up our friendship was closer than ever. one girl that i have been friends with since i was in first grade named victoria tryed to break me and kiara apart and me and victoria got into a fight in the middle of the street. now i am currently friends with kiara and victoria and today at lunch they said they wouldnt sit with me because they wanted to talk about something private so they didnt sit with me and then in the hallway after the last bell rang i ran over to kiara and i didnt get the chance to say anything and she just blurted out sorry i cant hang out with you im hanging out with victoria. so i walked away then i saw victoria, kiara, rapheal, nick, and joey walking in kiaras house when i got home (kiaras my neighbor) i dont know if shes mad at me or shes just being a ***** and doesnt want me hanging out with her but i feel very left out and i feel like no one wants to be my friend and that im all alone in middle school. i feel like a complete loser. can someone just please give me advice on what to do?