Hello and thanks for your letter.
It sounds like you are feeling quite lonely at school and would like your friends to be closer. Have you been able to speak to any of them about how you feel and about maybe doing more things together? Maybe you could come up with an idea and ask them to join in.
It can be difficult to make new friends and it does take time to get to know people. Why don't you ask your new friends if they may have similar interests to you, like going to an after school youth club, the cinema or even a hobby? It could mean you have more time to get to know each other.
You also mention your old friends - have you been able to keep in touch with them? You could try emailing or texting them and perhaps they would have some ideas of how to get your new group a bit closer.
Check out the ChildLine message boards and post a message to see what other young people in this situation have done.
Good luck and take care
Sam