Pumping question

For those of you who pump (exclusively, while you’re at work, or just whenever) how much do you usually pump per session?

My daughter easily drinks a 6 ounce bottle but I never am able to pump 6 ounces in one sitting (except first thing in the morning where I get 8-10). I am going back to work at the end of August and worried for what this means. Any tips on pumping more? I am not against using formula but would like to do as much breastmilk as possible.

For reference, I Already pump after every nursing session to try to increase my supply. My daughter sleeps through the night too. She will be 5 months on the 20th. She also has a dairy allergy so I’m on a dairy free diet!