You don't need to tell T on the first session. With my first T it was over a year before I told her. My current T, I told her about 5weeks after our first session. She had asked me several times because of my history with EDs and self injury. When I finally told her she said she noticed how relieved I felt and how she knew I'd tell her when I was ready. We haven't discussed it much because she said we need to work on making sure my depression & anxiety are under control first.

Let us know how it went.