The first step is to fugure out if you have a supply problem, a pumping problem or both. Since your baby is happy at the breast it sounds like a pumping problem. NOT unusual-- I've known a mom who breastfed twins (and tandemned part of THAT time with their older sister!) but who couldn't get squat out with a pump!
First are you using a GOOD pump, like a Pump in Style? If you're using a PIS are you using the shields that came with it? In my experience it's DEFINITELY worth the trip to Target or Babies R Us to get the SoftFit shields or the larger shields (I went back and forth betwenn the soft and the large, WHY they don't make them Soft AND Large is beyond me!)
Second, have you changed up your settings lately? I found it helped a LOT to change up the settings every now and then.
After those two things I'd start pumping during nap time on your days off and pumping the other side after you nurse. (I used to sit my pump bottles, shields and all in the fridge between sessions so I wouldn't spend all day washing them)
You can also pump last thing at night (you will NOT get anything much but it "puts in the order" for the morning) and then pump first thing in the morning before the baby gets up.
I LOVE nursing, but really struggled with pumping-- I could pump until I was "empty" and be all frustrated. 2 seconds later Isaac would decide he wanted to nurse and he'd sound like a frat boy at a chugging contest!
Oh, and when you do start solids in a few months -- schedule it so all the solids, juices and waters are given during your working hours. Anyone can spoon up the Gerber and it'll cut down (a little) on how much pumped milk you need. And skip the solids all together on your days off at first, the extra nursing will help protect your supply, it is NOT unusual to hit a pumping/supply slump after baby starts solids, so I would be sure and get this one solved before starting solids and making the problem worse.....