Hi Baby
First thing, don't worry. First few weeks of breastfeeding, the supply is inconsistent. Are you exclusively pumping? If you are, you'll have to work doubly hard in order to ensure your supply is sustained. If you can latch on, I suggest that you latch on as much as possible as that is the best way to help you increase your supply. If you really can't latch on, you may want to consider seeing a lactation consultant.
If you only want to pump for whatever reasons, then you'll have to massage through rolling and rubbing your nipples, and compressing your entire breast area very often, before and during pumping. By the way, after 2nd month, I'm an exclusive pumping mother because of spinal problems I can't carry baby for several months. My baby is exclusively breast-fed, and he's coming to 9 months next week.
As for supplements to take to increase supply, herbal supplements like fenugreek (can buy from GNC), more milk plus, mother's milk tea (think can buy from Moms in Mind) are said to help increase supply. Personally, I've not tried any of these.
I take Anmum milk for breastfeeding mothers regularly. I also take Scotts Cod Liver Oil tablets. For food, I drink longan and red dates tea (with a few other herbs) on a daily basis during my 1st month confinement and a few months after. I also eat pig's trotters in sweet vinegar, personally, I find pig's trotters very good in increasing milk supply. I've tried green papaya with pork ribs (I didn't try it with fish). I also eat ikan kurau almost everyday during confinement. Some ladies have shared that you should not eat pig's liver as this will decrease your milk supply.
Between weeks 2 to 4, you need to be very regular in pumping out your milk at this early stage, e.g. pumping every 3 hrs in the day, and pumping every 4 hrs at night. This is firstly, to establish your milk supply, and secondly, to ensure that you don't get any blocked milk ducts. This is the time when there is quite an increase in the amount of milk produced, so if your pumping yields much less milk and your breasts still feel hard, you may have some blockage. Do be careful about that as many of my friends had to stop because they didn't know how to handle blocked ducts.
Hope the sharing of experience helps. Paiseh, I'm very chiong heh.