Being bullied often effects kids for a long time. It’s difficult to trust other kids again.
Often kids who were bullied try to be “invisible” so they won’t be bullied again. It’s understandable. But what starts as self-protection can become isolating and lonely.
The good news is that you and everyone else is in a new school. My guess is that there are others who share your experiences and who are just as shy as you are. It’s a great chance for everyone to start over. Other kids don’t know each others’ pasts. You can decide how you want to be seen.
One way to get over your fears is to “pretend” you are more comfortable than you are. By acting “as if” you are friend material, you can become one. After awhile, you will feel more and more at ease.
Another good way to start is to join in an activity or sport that you like and just be a friendly, contributing person in the group. That takes the pressure off for making an instant friendship. By doing something together, people naturally get to know each other. Eventually a friend or two will emerge from it.
As for keeping friends, you might find it helpful to read this article: The Care and Maintenance of Friendship.
If you are still unable to make friends after making a good effort, do consider seeing a therapist for a few sessions. It may be that you need more help to get over the bullying than what I was able to say here.
I wish you well.