I used to be sensitive to perceived judgement, sensitive to criticism as though my identity rode on how I believed others saw me, and taken aback by what I thought was shunning.
I believe late teens, early adult years are not only most difficult, but also what can make or break many people. It's difficult, yet it's not where truth and awareness typically occurs. Can stunt growth like mad.
It's a time period, of envy. For instance, one could view you as having what they want and shun you, because they themselves lack foresight to realize the world is complex and each of us bears our own metaphorical cross.
With that said, how to read social cues? A person just sitting looking around quietly is more approachable than one aggressively speaking in a group.
It's perhaps easier to converse aside from the attention getter than it is to try and participate within their circle, as egos could bruise.

Confidence is to trust that you matter as much as the next guy, but without expecting privileges. Stay humble. Stay True. Sometimes it is nobler to listen and hear, than to be on the podium speaking.

As you gain your own beliefs, keep in mind, they are subject to change, remain flexible in growing/ maturing.