How are you starting your pulls? Run into a group with a shield lob, throw out 3 flashes immediately, then rotate between targets in the group with your combo. Do you have Marauder leveled at all? Foresight and Bloodbath will help keep you alive, every little bit helps.

One thing that can be a problem at these levels is that it may just not be your fault. Until you get Shield Oath holding hate can be an issue at times, especially with DPS that actively try to steal hate.