supply has gone down

Laura • May 14th due date!
Hi mommies! My little guy is turning five months old, and my supply has gone way down since I returned to work. I'm pumping every 3 hours during the day, and drinking tons of water, but it's 1/3 of what I was getting.
We will be out of frozen breast milk in the next two weeks at this rate.
Yes, I've been doing the mothers milk tea and fenugreek. 
Any advice???
Anyone try lactation cookies or bars that helped?!?!