I'm a level 11 mage. Was going pretty fast but now have drastically slowed down.

I use a V Earth charm with good EE... arena monsters die in 3-4 hits usually, but I'm out of mana by the 4th monster.
I have 877 mana, some mana/attack and mana/kill boosts, but those aren't really helping.

Any suggestions? Is my whole process here incorrect in some way?

Thanks for any help with this!

I would melee until lvl 15. Then at 15 start casting. Your mana will always run out pretty quickly, at lower levels you should be getting alot of shrines and just shrine those and keep going.