How bad is it to have a small liver ?

It depends on: Whether the size was due to medical condition like cirrhosis or just small by nature . If it is small and normal , you need not to worry . It can do all the job it is supposed to do.

Liver disease: A small liver that is caused by scarring is called cirrhosis. There are many causes, but primarily related to chronic alcohol use or viral hepatitis infection. The effect of cirrhosis causes impairment in production of proteins from the liver. It also causes impaired blood circulation thru the liver, which can make fluid build up in the abdomen (ascites) and create dilated veins in the esophagus.