Yes, you absolutely should throw those feelings out on the table. You have a right to them, you have a right to voice them...and IMPO he needs to hear that right now you feel he's just "going through the motions", even if you don't ALWAYS feel that way.
However...I do feel you need to bring up those issues he's not willing to talk about in your C-sessions. As I told my H one time..."it's often those things you don't want to talk about that are the key to the problem." If there's something he's not wanting to talk about, or is refusing to talk about them...why won't he talk about them? I konw you've probably asked yourself that same question, so ask it in the C's office.
You are going to the C for a reason, and paying dearly for it, don't hold back in there. I found w/my H when I stopped holding back what I was thinking/feeling we started to make real progress. Sometimes I let things out in the C's office because I felt safer there, I felt he was less likely to misunderstand me, and then the also the C knew there was more there than my H would talk about. She has the tools to get him to talk more easily than I could...perhaps your C does too, you just have to bring the things up.
