I, too, used Fenugreek to increase my supply, and found it wonderfully helpful. I also took Blessed Thistle, which was recommended to me by a lactation consultant. Another great product you may want to try is organic Mother's Milk tea by Traditional Medicinals (a tea blended for the needs of lactating women...read more about it at www.traditionalmedicinals.com), which I found at both Whole Foods and traditional grocery stores.
Other useful tips include making sure you are getting as much sleep as possible (love that one!), making sure you are well-hydrated and eating enough (try buying dried fruits, nuts that you like, granola and sesame sticks in bulk and snacking on them while you are pumping/feeding your child), using a powerful breast pump at work in a quiet, private space with any relaxing aids you can use (maybe some white noise, lullabies, a recording of your baby, a photo of your baby, etc), and, if you aren't dealing with cracked nipples or other contraindications, pumping beyond 20 minutes...ideally until you have a second let-down (I realize this may not be possible at work, in which case I would recommend pumping AFTER breast-feeding at home). I know this sounds like an overwhelming amount of work, but your body will respond quickly and then won't need to do it again until the next time you need to increase your supply!
Another trick: this weekend, try spending the day in bed with your baby. Get your husband or a friend or relative on board to help with any errands/chores that have to be done, and have your meals brought to you in bed. (All those friends/relatives that keep offering to help, but don't know how to be helpful? Use them now!) Allow your baby to nurse as much as he or she wants to for at least 24-hours and your body will increase production!
Good luck!! (And if you have any further questions for me, I'm happy to provide you with whatever information I can!)