I was with my previous T for 13 years. I told her the big things, and some were difficult. Some were things I had never told anyone else, ever. But there were still many things left un-said because I...just...couldn't. I wish I had been able to tell her "hey I have things I know I should bring up, but I can't say them outloud".
I didn't know then what I know now that it was a transference issue (maternal) and I was afraid of her judgment. Although, she never, ever, actually did judge me, I just thought she would.
I'm working with a new T and hope to trust more and bring up issues like transference or fears of talking when they come up.