Pumping work schedule?

Ashley

I’ve been at work for the last 2 days. My shifts are only 5-6 hours depending in morning/afternoon shift. I’ve just been pumping 2.5-3 hrs after her last feed before I leave. Is that what I should be doing? Or more often? Or just pump when I start to feel full? I’ve only been able to get 3oz total from both side each pump session while working? She’s 6 weeks, so is that a normal amount?