Pretty normal as for how much youre pumping, and its likely that baby is getting more than that.
How is your let down? Two things come to mind: overactive let down (babys choking on your let down from it being so strong), or possibly something in your diet. Also - some babies are just spitters, even when its projectile. But I would consider looking at your diet as a possible culprit before jumping to any other conclusions.
Also - its not uncommon for babies to take about 2 weeks to get back to their normal birth weight. When checking his weight - make sure its on the same scale each time, and its under the same circumstances (no clothes) - and I recommend always nursing just before
If you are concerned though - put a call into a local LC and see what they say as well
Lala...