From what I've read (I was having gallbladder pain last month/possible stones)you need to make sure you drink enough water daily, eat enough fruits/vegetables for fiber, and avoid fatty and high cholesterol foods. Without a gallbladder, you have a hard time absorbing fats. Bile is still produced by the liver, but it's released continuouly into the intestine. When eating a meal high in fat, there may not be enough bile in the intestine to allow for proper absorption.
Did your Dr put you on a bile acid supplement to take with meals? A Vitamin C supplement is good to take if you still have your gallbladder in order to prevent the stones from forming because it converts cholesterol into bile acid.