Do the stories you tell seem to come up organically? Or is it a pause in the conversation that you fill with, "I went to high school with Left Shark, and this one time..."?
Also, perhaps you need to make a point of asking other people about their lives. Maybe you already do this, but it's something to consider. Next time you see the group organizer, ask him about his life? And try to do so in a way that doesn't give the impression you might be comparing yourself. Maybe ask about things beyond music experiences and accomplishments, as that can easily come off as trying to see if his are better than yours. Ask how his weekend was, discuss his hobbies, etc. Resist the urge to share your stories, even if they are great and relevant. And when others do tell stories, don't always share the related story you may have. Engage them on their story. Let them have that moment. Don't try to be interesting or funny or clever. That said, maybe Organizer-Guy is just not a fan and never will be, and that's okay, too.
I've lived overseas for the last 9 years, and most of my closest friends at this point have lived overseas as well (which is how/where we met). It's always a topic of conversation among us that we worry we sound douchey because so many of our stories start with, "In Japan..." or "The Germans have..." or "When we were in the Netherlands...". To us, we are just discussing our life and there is no brag intended, but we are all keenly aware that because our experiences are unusual and, to many, enviable, it can very easily come off as boastful. We have discusses how we all make it a point to censor ourselves a bit. We don't hide our experiences, but sometimes we leave off the location of stories, or opt not to tell those stories if we've already told other related stories.
