I remember going through something similar with my baby during the first month or two (bubs is now almost 4 months) when he was nursing really really frequently and I wasn't even sure if he was getting any. But I found out that sometimes, they nurse like that, not b/c they are really that hungry, but so they can help bring your milk supply up.
Also pumping is only an indicator - it's not a completely accurate picture of how much your breasts produce. (First bubs can get at least 30-40 mls more with sucking and secondly, milk flows more easily with nursing - esp if like most moms, you find pumping stressful.) Even now at 4 months with a stable milk supply, there will be days when I can pump a lot at one sitting and days when I get less than half that amount. I've learned not to worry so much about it and that in itself helps. (Stress can cause you to produce less milk.)
The key thing is to keep nursing as much as possible. When I'm with bubs, I will always nurse him rather than give bottled EBM. Even for the dream feed that my husband gives to bubs, (and I use that time to pump for next evening's feed) I will always put him on my breast after he finishes the bottle (and I'm done pumping) - even if it's just for a few minutes so that he can get extra hind milk and my breasts get the extra stimulation to help maintain supply.