Have you tried meetup.com? Maybe there's an event or group that catches your eye.
Usually the problem is you join a group that already met a few (sometimes many) times together and you're the odd one. Of course some groups try to be really inclusive but that's not always the case. Rarely you feel confident enough to engage in the topics discussed etc.
I guess it might be a cultural thing. Possibly it works better in countries like US.
The problem with meetups is that you don't have the common activity to help with really interacting between each other. It's often a presentation and then some networking but networking events at meetups don't help introverts at all.