I’ve always had this problem. I’ve learned it has little to do with me directly. Or more to the point, I create it myself by not following all the social protocols necessary to be included. That is, most people aren’t thinking about who to include, they’re just doing what it takes to make sure they are included. Meanwhile, I was waiting around for someone to reach out to me, which often gets interpreted as arrogance or indifference.
Or, put simply, other people don’t think about you as much as you think they do. If you want to be included in something, it’s up to you to insert yourself and be noticed. And it’s important to be easy to be around, which isn’t always easy for us ADHDers.