Yes, you are fine to go to Naxx.
However, you could use some upgrades:
-Wyrmrest Chestpiece (seriously, Icebane? It's nice you have it, you'll need it for Sapphiron... but in heroics, you don't tank wth that do you? It has no defense! There are much better options).
-Titanium Earthguard Band
General overview of gear you can shoot for while still doing Naxx:
-Reg HoL - defense trinket
-HVH - bolstered legplates + lavanthors talisman
-HOK - better ring and epic bracers
-Gun'Drak - better gloves, better shoulders, trinket
-HUP - red sword
-heroics in general for badge dodge trinket
I would also recommend rearranging your enchants/gems. Just because the cap is 540 doesn't mean its pointless to go above that. If you're smart, you can get to 545ish and then start stacking Stam, or Dodge, or Parry. Whatever you prefer. Or its just personal preference.
Best of luck, hope this helps