Even the Ts that do the deep past stuff don't necessarily need you to tell them everything. It just kind of shows itself.

For example my T tugged at my sleeve the session before last while explaining something. Next session I told him I didn't like that because his hand turned into my father's hand and I felt threatened, like prey, but I froze and said nothing. If I hadn't already disclosed CSA I think he could have worked it out from that.