Singel target Mage rotations are all easy.

Frost
Frostbolt
that's it.

You can advance your rotation or spell selection with higher level if you want.
Adding following skills
Frost Nova Rotation for Shatter (non bosses) (a small damage increase)
Fire Blast for finishing / runners


Fire
there are different options

x) Castsequence 1-3x Scorch then Fireball (depending on mages and specc)
x) only using Scorch (1,5sec cast, you have to spam your button )
x) only using Fireball (if you dont take Scorch talents)

with PoM you can add instant Pyroblast
you can also add Fire Blast for finishing / runners
you can pull with Pyroblast


In my opinnion as Multiboxer you should make your rotations as easy as possible to be most effective.
Mage is the easiest class for doing this. Both Frost and Fire are very strong.

I can't help you with your specific level or your setup. I didn't play without a tank.