If you pump full time during the day you MUST MUST MUST nurse as much as possible when you are home. The pump is not as efficient as the baby in getting the milk out, so if you are pumping only, you will have an extremely hard time keeping a supply up. Fenugreek is available without a script (not sure if you meant you had taken this with a script or a different script) and available at most health food stores. Here is a page about it and what dosage you should take: http://www.kellymom.com/herbal/milksupply/fenugreek.html
Also drinking lots of water and getting good nutrition help. Also some say that eating oatmeal (not the instant kind) helps as well. Try to give formula as little as possible because that is reducing her demand...and nursing is all supply and demand. 2 oz per side really is not bad...a child that age really shouldn't be taking more than a 4 oz bottle.
Also, you want to pump at least 3x in a 8 hour day. I pumped for my first son for 14 months and I did have to use the fenugreek off and on, but as long as I kept up nursing well when I was home, my supply would always come back up. I think about that age I also fed 3x a day by nursing, once before I left for work, once when I got home and once before bed. There was a feeding or two in the middle of the night as well.