my supply is practically gone overnight?!

Shelby
I need help! My son is 3 weeks old and I want to continue breastfeeding however we had to start getting him used to a bottle due to me going back to work soon. We decided we would only give him a bottle at night and I would breast feed during the day. I went to pump early this mornings free he took his bottle and I am only getting MAYBE 3-4 ounces by just pumping where before I was getting 4-5 AFTER feeding him. I want to continue breast feeding for as long as possible but my husband is thinking we may have to start supplementing with formula. 😢I have been drinking the tea, lots of water any other ideas that helped bring your supply back? And how long did it take? I know that right now 3-4 oz is about normal for 3 weeks old but it seems like my supply is continuing to decline. I also need to get milk storage built up for when I go back to work.