You have a couple options open to you, but some aren't the greatest.
1)Quagmirran's Eye - Right now, it's good but not massively so. However, there comes a point in gearing oneself where it becomes even better(the haste proc is more useful as your gear improves). For me, it's ranked as number 4, iirc.
2)Shiffar's Nexus-Horn - As mentioned, it's a good trinket.
3)Xi'ri's gift - Work on that Sha'tar rep. You need it for a helm enchant anyway.
4)Icon of the Silver Crescent - As mentioned, it's by far your best option right now. Go for it. It'll last you quite a while.
5)Timbal's Focusing Crystal - It's actually a very good trinket for a fire mage. Though not nearly as good as it is for Affliction locks and shadowpriests.
6)Battlemaster's Audacity/Alacrity - Both are rated higher than either of your current trinkets, sadly enough.
My recommendation: Farm up rep and badges and get both the Xi'ri's Gift and the Icon of the Silver Crescent. However, plan on working to eventually have both Quag's Eye and Timbal's Focusing Crystal too(replace Xi'ri's Gift with the latter when you get it).
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