You're not insane, I think it's not uncommon to worry about things like this. Unfortunately the worries do end up being true on occasion, too. But I don't know if there's any way to know for sure with just the information you have right now, it's possible you're taking it personally when it doesn't actually have anything to do with you and your brain is cherry-picking events from the past to confirm your theory. Perhaps you could try waiting a bit and asking them if they're bothered at all by your loud personality to test the waters. Just say that you've been worried about it but don't mention anything about the other group chat or them meeting without you, that way you're not being accusatory, so hopefully they feel more at ease to tell you how they actually feel.