I have an umbilical hernia. I recently had a d-dimer done (for a different issue)and it was totally normal. Does this mean I'm clear of liver disease?

Not related. An umbilical hernia is just an out pouching/defect in the abdominal wall. It can be congenital (born with) or acquired - in either case, it is not diagnostically valuable in looking at liver disease. The d-dimer can be used for a couple of different illnesses, but again is not specific or sensitive for liver disease. Sorry but neither finding tell you anything about the status of your liver.