Your description of the disassociation you went through as a kid mirrors exactly what happened to me. Around the same age, I consciously just shut off. Stopped caring about anything or anyone. Then very slowly over the next few years intentionally but cautiously let things back in. I also have no memory of my childhood really. Just a couple flashes and images. If someone describes something, I can sometimes vaguely remember that it happened but no more details beyond that.