If the baby fussing for more, or you just think she needs more because she's growing? Most babies needs stay level actually. They take about the same amount from 1-6 months, and even after that when they are older than 6 months they don't need more because they start taking in a little bit of solids. (http://kellymom.com/bf/pumpingmoms/pumping/milkcalc/) So if she's not fussing, she's probably fine. If she is fussying for more, then here's the increasing supply advice:
Everyone is giving you great advice: oatmeal for breakfast, mother's milk tea, make sure you are drinking lots of water.
Also, although you seem to be pumping quite a bit - pumping 12 oz per day is really good - you might see if you get any more if you pump longer or at a different setting on the pump.
Things that worked for me were:
1) pumping for at least 20 min. I would get a good letdown of milk right away, then at about the 10 or 15 minute mark, I would get another big letdown. A friend of mine did something similar - pumped through the 1st letdown. Then turned the pump off for 5 min. Then pumped again and got the second letdown.
2) Although I most often worked at my laptop while I pumped, I got much more milk if I stopped working, relaxed, and looked at a picture of the baby and kind-of imagined him nursing.
3) Make sure you aren't turning your pump suction too high. If it is high enough that it hurts even a little, you might be tensing up which can make it harder for the pump to get the milk out.
A last thing - try pumping first thing in the morning before you nurse. Most women have the most milk in the morning, and can pump a few ounces (not until empty, but maybe 2 or 3) and still have enough for the baby to nurse until content. Then you would have a little bit of extra if needed.