If you want to play arcane on this fight, feel free to play arcane. Here are a few logs to look over if you want.
A slow normal kill just helping some friends out https://www.warcraftlogs.com/reports...pe=damage-done
A heroic speedkill https://www.warcraftlogs.com/reports...pe=damage-done
An average heroic kill https://www.warcraftlogs.com/reports...pe=damage-done
On all of these I'm using ice floes, prismatic crystal, supernova, and incanter's flow. My biggest suggestion is working on managing your ice floes properly. You should very rarely actually have to cancel a cast if you correctly manage ice floes, and if you're having trouble doing damage with arcane, It's some combination of problems with gear, mana management/rotation, or movement. Your gear isn't crazy, but it's at a solid level, and if you're unhappy with your damage on just this fight, then it's most likely not a problem with your rotation, which leaves movement as the most likely thing holding you back without any logs for us to look at.