I play on a Classic Server

I am currently level 25 on my Druid Tank, 2 Mages, 1 Priest and 1 Warlock and currently running Stockades. I have no issue clearing mobs 3 packs at a time with single target; however with AOE it is a bit underwhelming. It takes me 3 casts of Blizzard, and rain of fire to get them to die.

Is that normal? Are my expectations too high for this team to AOE in Dungeons?

Should I reroll a paladin tank and another Mage to make this threat easier and AOE more significant?