No clue but you might want to get her checked out. That cant be good to have memory loss at 5. Hope your guys life goes up from here. All the best.
Any traumatic experience can impact on people at any age. That might not neccesarily be depression. It would be worth taking to her a doctor to have physical causes ruled out and then a child psychologist who would certainly be helpful and they could see if further referrals were needed.
I'm sure all she been through has manifested itself in her somehow which needs to be addressed. She's so young to have nedured so much. Get her to the pediatrician and go from there. There may be something else going on, and all this has to be affecting her school work, and her ability to function as a 5 year old. I hope both your lives continue to improve, and never stop moving forward. You and your daughter deserve stability and happier times and she is totally dependent on you to provide this. Take care and be strong.