The reason I was asking about your care situation, is because some moms can juggle around the times of feeds/bottles so that the DCP does not need to use quite as much milk.
Do you know how late the DCP gives dd her last bottle? Could she try to hold her off, and then you could nurse her right when you get there? What I am thinking is that maybe you could suggest trying smaller amounts during the day. Instead of giving her two six ounce bottles at say 10 and 2, could you try this:
Leave the house a few minutes earlier and shoot for a feeding at the sitter's. Would she nurse for you again at 7am, or a little before...maybe if you tweaked that 6 am feeding. Then she might be able to make til closer to 11 am before the first bottle. Then she could try 3oz. If she wants more then try 1 more oz. or 2, but not a full 6 all at once. So if she took the bottle at 11 am, could she take the next bottle at 3pm? Again, shooting for a little less to start. Then when you get there right at 5 offer to nurse her before you head home.
You have two potential helpers here. Offering less milk at a time, and getting her to nurse possibly an extra time during the day, which would be great for your supply, plus helpful for stretching out the EBM that you have for the day.
These are just thoughts and ideas that have worked for some moms in you situation. Please let me know what you think!