Drop in Milk supply

Hi mummies, my LO is turning 1 month in a few days time and I noticed a sudden drop in my breast milk supply since few days ago. I used to be able to produce at least 200ml to 240ml total for one pumping session but now I can barely produce 190ml total per session. Any mummies experience the same? And is there any way I can increase my milk supply? My LO refuse to latch so I am exclusively pumping.