Not gonna happen, this is how ele shamans were. If you expect to spam Chain Lightning on single target and not expect to go oom that's how they're meant to be. Mana was put there so they can't just spam an aoe based spell constantly without penalty. However, the mana generation from chain lightning on a group of 4 or more is quite insane.
Ele shamans like boomkins have issues in pvp when focused, live with it. Sorry but warriors, dks and rogues will shut you down unless you are sneaky and one step ahead of them.
Fulmination wasn't a nerf, it was a fix, pls use the right term. Your best bet for damage as an ele shaman is Elemental Mastery procs off Lava Burst now in pvp. In pve, they are extremely wicked but underestimated.