Is there any chance of you getting another pump break during the work day? That would probably be the most effective way to increase supply.
You could also try pumping after nursing when you're home with your baby, and/or right before bed if your baby has a long stretch of sleep at night, and/or in the middle of the night if she sleeps through. Just getting a couple more oz in the evening would get your closer to that 8 oz you need...
If it makes you feel any better, I once spilled 5 oz on my freshly cleaned carpet. When I was struggling with supply and supplementing with formula- which just made it more painful.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"