Like you say - you don't know you are doing it, so how do you stop doing it?

You have stated that it is caused by stress and anxiety, so these are the issues you have to address. You have answered you own question here, because you have already taken steps with your counsellor to help deal with these issues. I'm not saying it will be easy, or quick, but hopefully if you lessen the stress and anxiety, the teeth grinding will stop.

Good luck