Supply drop!

So we had a winter storm 3 weeks ago and I was off work for a week and exclusively breastfeeding my 4 month old. Before the storm I was pumping 25+ oz during the work day in 3 pumps. Since I’ve been back my supply has been drastically dropping and I don’t know what’s going on. My son eats 20oz while I’m at work and now I’m only pumping about 15-16 oz and I’m worried it’s going to continue dropping. What is going on?!?! I haven’t changed anything! I breastfed my first born until two years and had an oversupply the entire time. This one started off that way too. Any advice to get my supply up or ideas for what could be causing the drop would be appreciated!