Breastfeeding to formula...

No judging please..
My baby is 2 months old today and I was exclusively breastfeeding. I started pumping when he was 5 weeks to prepare him when I went back to work. He does fine with a bottle. Well I go back to work soon and I'm afraid he'll run out of milk. When I pump I'm only getting 1-21/2 ounces of milk. In order for me to get a lot of milk I have to wait 1/2 hour after he eats to get the 21/2 ounces. Then as soon as I'm done he's hungry and barely gets anything. I know the more you pump the more you'll produce but when I pump all day and only get 3-4 1oz of milk that's not enough for 6-7 hr shift. He eats 2-4 oz each feeding. So now my question is, those on WIC. How did you tell them you wanted to supplement with formula? I want to use every ounce of milk but 1 oz won't fill him up. What I have in my freezer will last 2 feeding a and he eats every hour to an hour and a half.