When I hold back, it is generally about my fears about the topic itself. Once I get past that point, I don't hold back. Sure, there are topics that are more uncomfortable to discuss, but there is a reason for that, so in session having that discussion is probably where I need to be.

That said, there are things that I don't share with T because they have nothing to do with my therapy. I don't subscribe to the idea that you have to tell your T everything about you. Some things just don't really apply I guess. If somehow those things became relevant, I'd talk about them then, but so far that has never happened.