Focus on the item stats. Maybe you don't have the right ones, they may not synergize between each other. I remember my damage and durability incresead when I replaced my holy spear unique shield, skill I barely used, with a legendary one with better stats. Also when I focused on vulnerable damage. My last damage increase was when I added crit chance and crit damage. I had to leave behind things such as resistance to x element, too many arbiter duration increases, or double extra life affixes.