Is my baby over-eating?

You can't really overfeed a breastfed baby. At this age they are still getting used to the nursing and helping your body adjust to know what to make. Your LO could also have a growth spurt coming on and be nursing more to up your supply. Keep pumping and when the baby slows down, hopefully you will be able to pump more.

Pumping doesn't always work that great for some women and some babies. With my first I could pump 8 to 10 ounces out. But with the second I could only get a couple. Watch your baby and just think about how precious he is - that should help the milk flow. It seems strange - but it is true. The more I think sappy thoughts about my baby - the more the milk flows. :)

A breastfed baby really can not overeat. Is he actively nursing the entire time, or is he using you as a pacifier once in a while? And as far as the pumping, pump one side while he nurses on the other - that will help big time with output. Make sure you're staying well hydrated, eating plenty, and try some of the milk-producing food boosters like oatmeal, mothers milk tea, etc, if you aren't already.

The "rule" for a baby that young is to feed when they're hungry. And babies go through a LOT of growth spurts, when they eat like two times more than usual. The first one happens around 6-8 weeks, so that could be it. If that's the case, it'll slow down again. If your supply is having trouble keeping up, you could always supplement with formula when the feedings get too demanding.

at 6 weeks I wouldn't think any baby could overeat.

There's no need to feed a baby more than 4 oz. of breastmilk in a feeding--their bellies are just so small! If you're feeding at the breast, baby will tell you when s/he's done, but if you're bottle feeding your breast milk, choose a limit. I've noticed that if my son eats more than 4 oz, he'll generally spit most of it up. If we stop feeding at only 4 oz of breastmilk, he rarely spits up...