I feel this way a lot too. I always heavily prepare what to say, to the point where I write it all down and then practice saying it out loud. My T has also suggested I come in without any preparation. It sounds appealing in a way because I wonder what would happen, but in reality I think it would be a disaster because my brain becomes mush in therapy. I can't think very well. As other people have said, it is completely up to you how you want to spend your sessions. If you think that coming in unprepared is not your style, then that's okay. Everyone is different.