It takes time for people to work up the courage to go to events, but everyone I know was glad they did, even if it was awkward for the first half an hour or so. What might help is messaging the organisers, who will almost certainly assuage your concerns about wanting to impose. I've never met an event organiser who didn't want new people.

Being in your 30s is definitely not old, in fact that's perfectly normal by kinky standards. Why do you think so many TNG/Under 35s munches and events exist?

It sounds like you do have self confidence issues though, I'd recommend some self help cognitive behavioural therapy to learn to catch your brain when it jumps to negative conclusions like 'Nobody would want me there' or 'I'd just be a bother'. I recommend 'Mind over Mood, change the way you feel by changing the way you think'.