as-salaamu alaikum wa rahmatullah my dear little sister,
True friends are like rare gems or roses in a garden- they are hard to find but beautiful when you find them!
You'll meet a lot of people in life who harm you or benefit you. But it's YOUR choice how you react to them.
You can either get sad or feel sorry or you can get up and do something fun and take control of your life and situation.
Some ideas: hang out with a teacher at lunch by playing games or helping in the classroom, play more group things at recess and it doesn't have to be with the girls who you already know, read a nice book in the library, etc....
Most of all, remember the Highest of Companionship- of Allah (swt). If He is your friend, the entire world doesn't matter..
If Allah loves you, remember, He will put love and mercy in the hearts of people towards you. (we know this from an authentic hadith- maybe someone can post it here) So aim to get His love and the rest is........history

take care! and remember, you are an awesome girl!
Zahra