Regardless of whether my audience knows about my past, I use neutral words to refer to my childhood. I don't use gendered pronouns at all--avoiding them is easy because I'm talking about myself--and instead of calling myself a girl or a boy, I say something like "when I was little" or "when I was nine" or whatever.
If I have to use pronouns, though, I use he/him/his because as far as I am concerned, I was a boy back then even if nobody knew it. I mean, if I had ever been a girl at all, EVER, I would not have needed to transition in the first place, would I? I transitioned BECAUSE I was a boy already and wanted to be perceived as one by everyone else.
How do you refer to your past self? What's your rationale, especially if you think of yourself as always having been a girl (if you are MTF) or a boy (if you are FTM)?
I'm particularly curious now because I've begun seeing a new therapist who uses "little girl" and female pronouns to refer to my past self. He has done it twice now, and he is well aware that I find it hurtful. I'm not sure why he does it, but he is not queer, nor does he specialize in gender identity issues. I'm thinking that maybe he hasn't seen things from my perspective. Anyway, I'm planning to talk to him about it soon, but I'd like a bit more ammunition for my perspective before I do.