you should try opening with blizzard 3

something like: Blizzard 3 -> Thunder 2 -> Fire 3 -> Fire 1 -> procs/Fire1 til under 1.1k -> Blizzard 3 -> Thunder 2 -> Fire 3 -> Fire 1

^what happens with this rotation, is that you get the hidden cast speed buff from UI3 while casting Fire 3, but due to the delay in hits/buffs/debuffs registering with this game, you retain the UI3 buff when you start casting your first Fire 1 so it's also cast faster than normal (about one second) - but midway through your Fire 1 cast the game registers that you've cast a Fire 3, and applies the AF3 buff to you - giving you the full damage bonus on your first Fire 1

this is referred to as double dipping, your initial Fire 1 receives the bonuses of UI3 and AF3

also, don't ever ever ever bother casting a second Blizzard spell after your Blizzard 3, it will always be a dps loss, either follow it with Thunder 2(gives you enough time to regen to full mp), or if you had a thundercloud proc towards the end of your burn phase don't bother reapplying Thunder 2 as you should've applied a Thunder 3 with your proc, so just follow the Blizzard 3 with a scathe(incurs global, also enough time to get full mp) before going into your Fire 3 -> Fire 1

also also, you should never hard cast Thunder 3 on a single target - there's a bit of an argument for using it on trash packs if you're casting it on multiple mobs, but single targets Thunder 3 should be reserved for procs only.

also also also, you shouldn't be using transpose at all in your single target rotation, Blizzard 3 effectively replaces it.

aoe/trash packs is a different story, you can find uses for convert/transpose/flare/all kinds of stuff