Returning to work and EBF

My daughter is 12 weeks old and is sleeping through the night. I usually pump once a day in the morning on one side and feed on the other (I've been block feeding since birth-feeding on just one side- due to oversupply and fast letdown as recommended by a lactation consultant). I usually get about 3-4 oz on one side.

Right now I only have 4 feeds worth of milk in my freezer and I go back to work in one week. My daughter will need to eat approximately 3-4 times while I'm at work.

I'm so nervous about pumping during work and I'm terrified I wont pump enough supply for her. She's never had any formula so I'm worried about her babysitters (my grandma and my father in law) having to give her some as a last resort. My lactation consultant said that I have an intense response to nipple stimulation and it has repeatedly caused oversupply when my daughter has a growth spurt and feeds more often so she recommended pumping just once a day when I'm at work but it just seems like that won't be enough.

Do y'all have any tips on returning to work? Or on combination feeding if I have to resort to that?