Nothing wrong with PvP gear if you have no better option, it has all the stats of PvE stuff with PvP stats added on. I figure the 483 PvP piece is equivalent to the 483-level LFR piece without the tier bonus.
There is a tank helm that can drop from the bag, but your DPS helm is probably OK.
The Ghost Iron Dragonling is nice, and I didn't stop using it until I had an LFR Agi trinket plus a heroic Agi trinket. I could keep one of the Brewfest trinkets in my bag for ilevel, but it isn't actually necessary any longer.
Even more important than the ilevel is making sure you're getting the best stats per piece, especially as a tank. Everyone should prioritize the main pieces of armor with the most stats on them: helm, chest, shoulders, legs, followed by gloves and boots, then belt/bracers. I could have padded my ilevel even more by getting the cheap cloak and ring, but I opted for the most effective upgrades rather than the biggest number.
You're not very far away from me at all. I think anyone who plays as much as I do will be pretty close, if not better.