This has been an issue for me, even with past therapists. I had one T tell me that it was a sign I was trying to control things too much. That I need to trust him that he will tell me when it's over. This current T has a timer go off at 5 minutes before the end, and I find that helpful, but I still sneak several peaks at the clock. T actually will reposition the clock for me so I can see it better, which I feel is very accommodating. I think it is a control thing for me. I like to be able to wrap up on my own terms. Being told to wrap things up (even in a nice way) feels rejecting to me.