Nurse. NURSE NURSE. The best way to build up your supply is to NURSE!

Pumping can help, but is not a replacement for nursing.
Fenugreek can help. But you don't need it. Besides, you don't want to be smelling like licorice!
Breasts have this really great system all worked out. The more you nurse, the more supply gets built up. It is a supply and demand situation. Which is why, after a day or two of not nursing as much, you start to lose your supply. It also goes the other way.
In about 1-2 days of more demand on your breast, you'll be making more milk.