LOL at the need to purge because it will feel good to the organizer in you!!
Well who would've guessed she couldn't wear 12 month clothes when turned 12 months?! I will be in the same boat, but with the opposite problem. Chase's onesies for summer may be too small because I bought all of them in 18 month...nothing in 24 months. He has maybe 2 rompers in 24 months. I hate not being prepared, so I bought ahead, too!
As for the changing table, I still use it every day. If I dress Chase or change him on the floor, it's a wrestling match to keep him on his back. I have to be super careful about laying him down so his head doesn't hit the edge of the raised gaurd on the table, but he usually draws his legs up anyway so he isn't hanging off at the foot end. Yet!
I bet Julia hits a growth spurt and you won't need to purchase warm clothes in 9 mos sizes. I can't imagine that! She looks long in the pics you post.