My ultrasound revealed diffuse increased echogenicity and coarsened echotexture. What does that mean?

It's Subjective. Generally, increased echogenecity indicates fatty infiltration, and coarsened echo texture (of the liver) could indicate cirrhosis (or hepatitis; among others), however, the findings are very subjective, cannot be graded and vary from observer to observer. If you have known liver disease (or even if unknown), consult a gastroenterologist for possible liver biopsy.