Your trees are looking good. I don't worry about what kind of pot a tree is in too much, unless it is going to be in a show. I use old chipped dishes, things I find at goodwill, storage containers, what ever the tree will fit in. For bigger trees I go to the dollar store and buy plastic oil drain pans. Anything that isn't too tall or that can be cut down and holes drilled in the bottom. For slip potting 2.5 quart nursery sized trees I use kids sand pails,they work great. For really big trees I use mixing trays that you can buy a home stores for mixing concrete. I try not to use terra cotta because they break easy in the winter.