It does not look like you have autoimmune hepatitis. The ANA level of 1:40 is very nonspecific, besides your liver biopsy did not show any hepatitis. The most likely problem is fatty liver.
You should try to maintain your weight based on your height. Also get yourself tested for diabetes and serum lipid levels and if these are abnormal, you should receive appropriate treatment.
Fatty liver is mostly a benign problem and you should not worry about it. Lead a normal life with regular physical activity (walks, sports).