9 months old drop in supply

Kasey • 🌈 baby boy born 9-20-18!

Ive been exclusively breastfeeding, mostly pumping because I work but he’s had breast milk only. He has a sensitivity to cows milk so I limit my dairy intake but my concern is the last week or so I haven’t been pumping enough to feed him the next day and my freezer stash is getting old/running low. I’m considering supplementing or just switching to formula full time but worried it will be expensive because it will likely have to be dairy free version. We have a pediatrician appointment next week so I’ll ask more then but wanted advice from other breastfeeding mamas. Is there some way to easily up my supply when my pumping schedule can’t really change?