I’ve heard of friends taking Domperidone medicine to help with supply issues. However, the effectiveness seemed to varies for everyone. Some found it effective while others had no success with it. One of the successful ones took four times a day, drank plenty of water and was also pumping more. Another friend took Fenugreek (from GNC) instead, 6 pills a day and felt that it helped. Some side effects from Domperidone may include headache, abdominal cramps and dry mouth. My friend had slight headache but unsure whether it was due to the medication. You can purchase it from pharmacies from Unity or Guardian or go through your doctor.
You can try Blessed Thistle capsules. My friend isn't keen on medication/drugs so she tried these herbal capsules (2 capsules 3 times a day) and she found that it helped with increasing her milk supply. You can get them at Watsons/Guardian or order them online from iherb.com or kulily.com -- retailing at around 10SGD.
thanks