Postpartum depression

Lately I feel like I just cannot cope. I have a son with with autism and a daughter that is 7 months old. Im worried about her development and i just cannot go through therapies and Doctors again. I'm losing energy and feel like a terrible mom. I can never go anywhere. My husband doesn't understand. I just want to feel better. Anyone else struggle with ppd? What helped? I already got a prescription from my Obgyn but it will take some time to get it thanks to insurance reasons.