Pretty hard to tell how you are doing at level 54 tbh... Make sure to upgrade ANY mail gear you have to plate by level 57 at the latest (when you can start buying level 57 outlands greens on the AH), and before you hit the mid to upper 60s at a minimum, all you really need is a TON of stamina. A little agilitly and strength won't hurt (Of the Beast plate items), and you won't really NEED spelldamage (soon to be spell power) for a while yet.
You probably won't hit 70 before the new tree comes out in a few days, so Losie's Prot sticky won't be AS valid as it once was, but it will STILL be a superb resource for you gearing up as a Prot between now and your first trip to Northrend, so I recommend you read it a few times now just to see some of the gear you can get and where to get it.
I just noticed when I checked your armory that you ARE 57 now, so start getting level 57 items off of the AH ASAP! You should be able to get your armor and health up significantly with a little work on the AH if you have the gold available. I would also suggest a faster sword to help you keep threat up a bit more. Other than that, not too bad for now :)