Welcome to Healthcaremagic,
From your query i understood that you are Obese and family history of Gallbladder
disease and now afraid of the same could be the cause for your Abdominal mass
As you are obese, you are more prone for gallbladder and liver
It could be a liver disease also.
Probably it could be a Liver enlargement ( as it is very large extending from left to right of your upper abdomen.
Better took an Ultrasound
abdomen to know the size of the liver and condition of the gallbladder .
Take blood tests such as Lipid profile
, Liver function test and liver enzymes etc..for liver disease.
Check your blood pressure.
Consult your Family physician with these reports.
Have Diet modification and physical exercise for better life.
Hope this helps.