Milk supply

Riley
Hi! I just went back to work on Monday and my milk supply has dropped drastically. I'm trying to pump as often as I can but it doesn't seem to be helping. I was pumping 3-4ozs and now it's down to 1.5-2. I started taking fenugreek today, does anyone know how long it takes to see results? I also formula feed which I know can be a problem but my little lady goes to daycare three days a week. TIA