It is psychological I see. This kind of "anxiety" comes from within, kind of fear of communicating to complete strangers. We are living in big cities, and we just do not communicate with people. Notice how westerners avoid even eye contact (in train, bus, public square etc.)? However back on topic.
This is different world, if you can't be yourself, make an experiment, change a nick on TS and play a new role. Join, say hello, say you will be here but only listening (aka "I speak no English").
It is like in RL aviation. Just same as pilots stay on local frequency, even that airspace class does not require to communicate with no one. It is good habit to listen to position reports and intentions of others. This helps you a lot to build situation awareness and new set of skill (radio coms). You will begin reporting own position and intentions shortly after... you'll see, that's even better habit :) Like with everything "The million mile journey takes one step at a time". I used to be fairly shy person myself. Now there are just days when I do not want to open my mouth at all, but that's different ;)
cheers,
Poko24