The woman in the "my mother" photograph is Sean Young
I posted this at a Blade Runner forum, and someone posted a close up and a similar Sean Young pose side by side. They were a perfect match. This is pretty unremarkable, however, the little girl who looks about 6, ("Remember when you were 6?") doesn't look anything like Sean Young. Interestingly the girl is wearing a nurse shirt with a medical cross on it. One of Rachael's memories is playing "doctor". Maybe most of Rachael's memories come from the girl, and she is in a sense Rachael's mother.