I'm pretty shy too and not very outgoing - but I still have a good time listening to bands, checking out the market stalls (if they have any) and meeting old friends.
Meeting new people I try and turn the conversation on them.
Most folks love talking about themselves
I'll be honest - this time may not be a blast - you may feel a little forlorn and left out (which is why not going is still one of your options...your group can get an uber or a cab) )
but, if you go, keep in mind this is not the best sobriety, or you, is going to get sober.
Work in progress. It gets better,
I didn't know the kids were that old - but tbh 16 yos probably still need a little adult guidance and supervision at festivals...in any case it's never a good look when the young'uns have to carry an old'un to the car but I did that more than once with young people I was with.
Utterly inconceivable selfish behaviour to me now - I changed and grew - you can too
D