First off, you sound like a lovely, smart person and I'm sorry your mum said those things to you, please don't take that stuff to heart.

I think the other posters here make lots of really good points and the only thing I want to add is that when you've got a charming person telling funny stories etc., the other person in the conversation isn't just asking questions, they're also providing lots of feedback to the talker through small gestures, eye contact, nods, head tilts and so on, to show they're fully engaged with the conversation. Keep watching like you're doing and you'll see it.

The girls you met who paired off may have created a quick, firm bond (like girls often do) because they were seated together away from you - nothing really to do with anything you did or didn't do.

Finally, as a quiet person I find it quite hard to talk at any length with other quiet people: half a dozen exchanges and I've hit my comfort limit. For that reason I usually gravitate towards chatty people where I can just sit back and enjoy being entertained by someone who's good at it!