How much do you pump?

I'm just curious if my supply is big enough... How much do you pump each session? And how often do you pump? I'm pumping every 2-3 hours and I'm getting 6oz each time... Its starting to get exhausting but I don't wanna stretch my sessions to 4-5 hours and loose what supply I do have! How does everybody manage the loss of sleep during the night from pumping?