Loneliness Support Group
Loneliness is an emotional state in which a person experiences a powerful feeling of emptiness and isolation. Loneliness is more than the feeling of wanting company or wanting to do something with another person. Loneliness is a feeling of being cut off, disconnected and alienated from other people. The lonely person may find it difficult or even impossible to have any...

I strongly recommend you look into some traditional martial arts like Aikido and Karate. There are different schools of both, some are very soft and ineffective, others are harder and more effective. You will not be able to defend yourself immediately.
But school is about to end for you, you will go to college or go find a job. The scars of bullying will remain in your psyche, those scenarios will play in your head over and over, and only a traditional martial art can cure them.
Also in long-term this training will make you learn how to dissolve conflicts without either attacking someone, or letting them attack you.
That's my intrusive opinion based on personal experience.
I don't know if I can be much help, but I know that it's nice having people to talk to you and make that extra effort when you really need it. So all I can say is that I'm really sorry that you are feeling this way, no one should! You are probably really awesome and you should have people to talk too.
(Sorry if this sucked or was offensive. Also sorry for my constant apologising, I can't seem to stop myself)
Please don't loose hope, let me say this when feeling depress just think of all the people that have less than you. That you are still lucky compare to someone your age that grew up not knowing or having a parent at all. What about a person born with disability like blind or missing body parts. You see honey you are lucky and blessed after all. Enjoy your life and love yourself . Try to be happy