1-3oz from one side is pretty good! Especially while nursing. Are you pumping because you're going back to work or for some other reason? Keep in mind that if you pump in addition to nursing, that you're producing above and beyond what your baby needs, so any amount is good.
If you're going to work, then you will probably be able to pump more since you won't be nursing at the time.
As for the pump not getting any more but you can...
what type of pump do you have?
do any parts need replacing (some pumps have membranes - little while pieces - that need to be replaced every so often, usually 3 months or so)?
how long are you pumping for? can you tell if you're getting more than one letdown? (I never could... but many women can)
Do you have the right size parts? the breast shields are made in different sizes that may fit women better (see:
http://www.justmommies.com/forums/f1...ld-flange.html (Are you using the right size breastshield / flange?))
Do you have the speed and/or suction turned up high enough? You don't want it to hurt, but you may need to turn it higher.
Those are just some things that come to mind...
Oh and I used to pump at work. I'd get anywhere from 2-7oz per session, double pumping for 15-20 mins (so that's combined, not per side)