F.L.
I also suffered from postpartum depression with my three children. They react to your stress. I know it is hard but try to calm yourself when she starts screaming and get down at her level and try to talk to her. My three and half year old is very demanding and the more I try to be the strong parent the more stubborn she gets. I have found the quiet approach on her level tends to work better and it seems to help my stress level too. If I remember to do it before "I overreact"
Hope this helps! Write back I have had lots of experience with post partum depression good and bad I would love to help!