I do the "I don't know" response also, probably a lot more than I would like and I almost always KNOW... I'm so glad your T has given you permission to say "I don't know" (even know you have every right to say that). I do understand be told not to say that - I remember those days well as a child. I still say it with a little insecurity - fear of what is going to happen. My T just lets it pass and tells me - when you're ready, you will share what you know...