Fabian i got to ll 24 mage in beta and i had over 2000 mp.
I would rest maybe once every 20mins if i had taken on 3/4 mobs in fast succession. and resting takes no time with a conured water
Maybe you need to rethink the way your fighting, or chang what you spent your talent points on (wish i could rememebr what i spent mine on

)
anyhow fights i would start with pyroblast this would often stun the mob then id get 2 fireballs off and that normally killed it, if it had caused a link id use frostnova to freeze him run back and cast frostblot then use fireball and fireblast to kill him, might take maybe 1 hit but mana sheild absobs that nicly.
with 2 links it gets interesting thats the point where you have to decide if you can or cannot beat them i had about a 60% survival rate vs 3 mobs (pulled mob+2links), running is easy just use frostnova and while running hit your absorb buffs to prevent taking damage, then return 20secs later and go again, normally you can take 1 of the mobs down so you onlygot 2 to deal with next.
Fighting Elites solo is that hard part, i had started doing that when the beta ended. Fighting 1 elite would leave me around 300-400 mana thats where the trouble is but its a wild fight soloing elites that are your lvl or a lvl above you
(Note i ended beta with 113 Int and 94 spirit on my gnome fyi, i think id crit strike 1 in 3 spells lol was great)