Milk supply...😑😞😪

My son is 14 weeks. The last two/three weeks since his last growth spurt I've been struggling to pump anything let alone the 4oz he needs. He is breastfed but I like to have milk stored for when we're out and stuff and I've had to start using my freezer stash which is stressing me out. What's the deal? For multiple pump sessions on both sides I get 2oz total on a good day where I used to be getting 2/3 oz per side 😭 I know pumping isn't a reliable way too judge how much you're making but it's still so discouraging and worrysome. I've struggled with ppa and was recently prescribed a low dose of Zoloft to help. Could that be affecting my supply? Everything I've read says no but I can't help put that and the timing together. Help a mama out, I don't want to stop pumping.