Increasing milk supply?

Any tips? I've noticed a significant drop in my milk production over the last week and don't know why. My diet is the same, I'm drinking enough water, so what gives. My son needs 22oz if I work. He gets 4 x4oz bottles (every 3-4 hours) while at daycare and at home and then a 6oz bottle before bed. Up until this last week or so I had been able to pump that much plus a little extra. Now I'm dipping into my freezer stash. I only pumped 14oz at work today and I'll likely only get 4-5 oz tonight before bed.

I've made lactation cookies- they used to help, but not so much anymore.

I eat oatmeal for breakfast.

I drink around 3L water daily.

What gives? Any tricks to try? I might try pumping after BF on Tuesday and Wednesday as I dont work.

*Kiddo still seems satisfied after BF on my days off. I just don't seem to be pumping as much anymore.