Friendships

When I was younger I didn’t really value him a friendships of relationships. Now I do value them and I find them important. I was friends with a group of girls after sixth form and then I distanced myself for a year. They become very close bc they only depended on each other. I become close with other people but I really do want to become friends with them again and be as close as they are to each other. This has worked as I now go out with them more and stuff however when it comes to like for example graduation I was not invited to their graduation but I think this is bc I did not invite them to mine. I did not invite anyone apart from family. There are four girls in this group. Theee of them are very close and one girl sees them every now and then. I wish to become a part of their forup, but I can’t help but feel sometimes I’m intruding or I’m not wanted or they just want to be friends them. What should I do?