You are welcome here in this group. I've read your post and also the one you wrote to it2ly. As you can see getting in with an existing group is not straightforward. A lot is the fact you have changed schools and are probably looking at people who have been together for years, got used to each other and hang together as a result.
There is a big drive to be part of a group and if you are on the outside not only do you miss the companionship and security, but it can make you feel you are lacking in some way -untrue but sadly part of human nature.
You do have one good freind and some others, and that is something special. It does not mean you are identical though, and if a friend is already part of a group you sort of feel like you should be able to just join up too.
Well, you probably can, but it is not an instant thing. Also that particular group my not be to your taste. Some like a particular sort of music, of games, of sport, well just about anything. You can end up bored witless with a bunch of people that go on and on about something you don't have any liking for.
I've been to many schools becuse my parents moved around a lot and I normally ended up with just one or two good friends, and not really being part of any group. I'd hang out with them if my friend did, but it was not that enjoyable.
Like you I'd feel out of it and wonder if it was me.
It is not a lost cause, later on when things settle down I was in a group, and I came to the conclusion it was basically time and common interest, we played D&D. I got used to them, they got used to me.It became something to look forward to.
Going back might not work as you expect, the people you knew before will have changed and adapted. Just remember the good times you had with them and look forward to the fresh ones where you are now.
Can I suggest you keep your existing friends but simply follow what you like and see what happens?