Oh, hey - my bad, you’re new. Let me help ya out here.
Mage is a class. Frost is a specialization.
If you press N (by default) you can view your specialization trees.
Currently the middle one labelled “Fire” is the highest damage dealing class in the entire game by roughly 15 entire percent! The biggest margin in the entire game. Wild, right?! - There’s a talent on the right hand side, 10 points deep called Burning Soul - Burning Soul reduces push-back by 35% per point, up to 70%! CRAZY!
The left-most tree labelled “Arcane” also has one! If you look at the first row, far right node called “Improved Arcane Missiles”, for 5 points you can be 100% un-pushable on your premier Arcane DPS spell. Arcane Surge is instant cast, and Missile Barrage will make your arcane missiles super-super fast!
But, you’re forgetting one super-duper important thing: In Classic WoW - shielding/absorption effects automatically remove push back while they last. Meaning, Mana Shield and Ice Barrier (both available to Frost mage!) will 100% prevent push-back while casting.
Though be careful! Face-tanking monsters and/or players will have a lot of damage done to your shield very quickly, removing them and making you vulnerable. You’re not face-tanking enemies, right? That’d be super reckless!
But if you’re super super dedicated… It’d be super smart to work on practicing utilizing the built-in slow, and root effects built into Frostbolt automatically to keep distance on enemies. Frost Nova is a great option for if you goof up and need a bail-out. Try not to use both Frost Nova, and Blink simultaneously, it gives up too much of your power in trade! Usually you can frost nova, step away, polymorph, create distance, and reset the fight for 100% free! You can use your summoned food/water to regenerate your health/mana. Then you’re 39 yards away with all of your spells slowing/rooting and having 100% automatic crit scaling + 50% increased crit! No other class can replicate that power.
Remember, though - Paper should always lose to Scissors. That’s part of the realistic trifecta of game balance.
Hope this helps! If you need some more pointers, WoWhead is a great source of game information.