Emily,
I think that communicating my needs to T is the hardest part of therapy. For some odd reason, I think we don't want to let them down or have them disappointed in us.
I am so sorry you aren't feelng well. I like the idea of leaving her a message on her voicemail. It will break the ice and let you get started with the topic that is hard to tackle face to face. Then you will feel like you are taking care of yourself.
I would write down a "script" about those things you are most worried about and just read it off. Then tell her you can discuss it in session now that the cat is out of the bag, so to speak.
Take gentle care of yourself.
