Those are good looking stacks of wood! I'll hazard a guess that they look even better to you since you are only in your second year!
If those 2x4 uprights start acting like they want to lean outwards, tie the two ends together at the top (with a stringer of some sort - just like you have done at the bottom with those 2x6s).
If you have the room, consider starting on the following year's firewood. That way you will never run short again since you'll be able to tap into the remaining stacks of wood.
After reading about the impressive stock piling that some of the AS members are into, I am going to make use of my land base (40 acres) and have "staked out" an area that I will endeavor to fill up with wood.
Great job and thanks for posting pics!