Your T will eventually learn to read you like a book, and vice versa. This takes time. You'll get there.

I had severe problems opening up to my T. Sometimes I still do. When I was unable to let myself say what I wanted to say, my T would ask me to say just 1 word about it. I would force myself to spit out that 1 word. Then T and I would play 20 questions. She'd ask me yes/no questions to try to figure out what I wanted to say. That quickly led to me opening up a little bit. Now I can talk a lot about it (whatever the it is at the time) after I get the 1 word out.

I also had an impossible time trying to lead the session. I hated it. My T recognized that, and no longer makes me lead the session though she always asks right away if there is anything I want to talk about.

Try to think of something that might work for you for opening up. Then present that to your T. You can also tell her that you are not ready to lead the sessions yet and it adds to your stress. Your T should be willing to work with you all accounts.