I did this when I first started out with T. He guessed at some trauma that I had not told him yet, and I lied and deflected away from it and told him about a different trauma that had happened instead.

I don't know why I did that at the time. It was automatic.

It weighed on me for a long time that I told T he was wrong about his first guess. Then recently after one session I said to T, "But there are some things I haven't told you." And he did not even react. He seemed to expect it and just said that it was fine and maybe soon I would feel okay to tell him. And I was able to tell him next session.

So I suggest just letting your T know that there is stuff you have not told yet and leave it at that for now. Just so T knows it's out there.