You can feel very lonely if the bullies have taken your friends away
Often friends are afraid they'll also be bullied if they go around with you. It's always very upsetting when friends turn against you which is a good reason to try to make as many friends as you can, even those in different years.
If the bully has taken your friends away you could have a word with each of your friends individually, at a time when nobody else is around, and just sound them out. You could try to get them talking about something they did at the weekend and then just say that you used to be friends with them and you're not sure why that changed. Tell them that you'd really like their support.
You're probably not the only one being bullied who has to spend break and lunch hour on your own. Keep your eyes open. If you see someone else on their own try to start a conversation, about anything, schoolwork, if you think you know their sister, if you think they might live near you, anything at all.
How to make new friends
To have friends you also need to be a friend and you can do that by trying to be open and friendly with people and asking how they are.
This isn't always easy because sometimes the people you are nice to aren't nice back, but if you just ask someone if they had a nice weekend then it gives them the chance to say something back and then you can try to continue the conversation.
People love talking about themselves so in time you'll find people who like doing that because you'll come across as a good listener and then people will enjoy your company and you'll find you have the same interests as some of these people which is the first step towards real friendship.