Late postpartum depression

I was wondering if anyone experienced developing PP depression 5 months PP? I feel like I did okay fighting it off before, but I’ve just been struggling the past month. My milk supply tanked and my son fell off the growth chart. I supplemented with formula, but I don’t think I was forcing enough. I started to struggle to feel like I was providing for my son and I’ve started to feel a disconnect. One of my friends can pump 10 oz every single time and I think it started to hit my esteem as I silently struggled. She would give advice, but I don’t think she understood how much I’ve researched and tried. I would just nod along and then go home and cry. Every day for the past week it’s gotten worse since I’ve made the decision to let my supply go. My son hasn’t been eating from me in a couple weeks since I can only get .25-1 oz each time I pump at work. I didn’t know you could start to develop it this late and I’m not sure how to adjust or get help. I feel stupid for asking for help when my son is 5.5 months. I also don’t think people realize how bad it is or that it’s even happening.