I completely understand what you are saying. I could have said those same words. Actually I was thinking of that before my session today. I was wondering what I could do to fix this problem as well. I could be talking about something very traumatic from a long time ago, that still emotionally resonates with me in the form of shame, guilt, sadness, fear, and anger; yet tell the story as if I'm talking about my trip to the grocery store. Sometimes there are situations that bother me all week that make me cry, frustrated, angry, etc. and once I am in the session all of those emotions shut off. It makes me wonder if T thinks I'm lying, or making matters bigger than they really were. It's also frustrating not being able to show her the extent of my emotions around the topic because it makes it difficult to fully heal from the experiences.
I'm sorry you deal with this too.

I think it is fairly common in therapy though.