Feel like my best friend acts different around me than she does around others?

I don’t know if this is just me making things up in my head but I feel like my best friend acts different around me than she does around others. I feel like she’s so much more talkative and extroverted with other people but when we’re hanging out just us two she’s quiet and introverted. I think she’s a naturally introverted person until she becomes comfortable around you but I’m feeling so paranoid that she doesn’t completely feel comfortable around me! Don’t get me wrong, I don’t hate that she’s quiet when we hang out but I notice when she hangs out with other people she engages in their conversation. I don’t get it. Maybe it’s just my own insecurities bc we’ve told each other how much we care for another and how we’re soulmates but I still can’t help feeling sad. Can someone explain this to me I just need another perspective