You can go ahead and call me stupid right now. Back in the day (2-4 years ago), casters used to complain that they ran out of mana. I asked them how much spirit they had and they laughed at me and said spirit is useless. I said back, you are the one running out of mana with no spirit, not me. They all wanted crit, spellpower and such. Fine, but if you have enough DPS, maybe you can use some spirit instead.

My idea is 96% of your spells can use either attack power and/or spellpower. So if you put on 2-3 int plate items, you get MP5 (which your is 19, no wonder you have no regen, you literally have 000000 regen). The int never hurts, the SP can be used in your spells and you get MP5 for free. All should help. You can make fun of me having a ret with a few SP items, but I am not the one running out of mana. You can even use a gear manager (built in or Outfitter) to swap out when you need more mana (bosses and such). I use 1 prot, 3 rets and shammy, the mana tide totem is pretty nice. If you are okay on health, you might set up for them to use a mana pot.

Also playstyle might come into play. If you use all your high mana attack all the time, you might not need to do that. Again, if you are okay on enrages or DPS in general, you might just take a few high mana attacks out and only use them when you need them. Just my 2 copper.