It looks like you’re doing everything fine. Judging from Warcraft logs. If you’re keeping beacon up. But if you want to really parse.
Keep beacon up on tank, beacon yourself. Keep the 15 beacons up and add an extra few beacons with regeneration as much as you can. Then keep spamming arcane blast/barrage/arcane missile when proc. Use Rewind time to snipe heals.
We have a lot of ways to get our mana back so try to use as much as possible during a fight. We have mana gem, and mana pot.
For some reason it doesn’t show you’re using a flask. But make sure to use ancient knowledge. You can add extra spellpower with boots with the leatherworking enchant.