I am running super low on my frozen breastmilk. I pump at work but I only get to pump twice a day…

I am running super low on my frozen breastmilk. I pump at work but I only get to pump twice a day and she's eating way more than what I pump. I am so worried that I'm going to have to give her formula when I run out. Any tips or advice on increasing my supply while I'm away from my baby?