For me, a lot of the work gets done whether I consciously do it or not. I think you've been thinking about your couples therapy or you wouldn't have "noticed" that you don't feel that you've done any work. Can you discuss any of it with your husband while you all are driving somewhere? My husband and I do a lot of talking while we're on our way to/from chores/engagements. Maybe he feels like he has been working or has some questions, etc.

As sister said, some just gets internalized and maybe you've done more "thinking" than you think you have :-) I would always go to the sessions though because you learn stuff during that time especially? And it's not cumulative or anything so you can learn new stuff or go over old in a different way, etc. during the sessions.