I can try. I wasn't sure where you said it but I was almost positive that you said it happened around 16. Maybe it was just a few months before she turned 17? Or even a couple weeks. That would explain her comment about doing normal teenager stuff at sixteen.
It took some reading through but I found it. She said the empathy was always there but really started to become uncontrollable at 17. So she was a vaguely normal teen up until then.