OK, so if you want feedback, here goes. Nice effort, but a couple of things...
The pot, although very very nice, is too small for the trees in it. The planting feels cramped at first viewing. It will get worse when the trees leaf out.
Negative space is EVERYTHING in a forest composition. Space allows the eye to rest and the brain to visualize a forest. It's as important to plan out negative space in a forest planting as it is to place trees. Ideally, identifiable negative space should be at least a third of the composition.
Additionally, the trees are mostly spaced too far apart and too evenly spaced from each other. Space between trunks should vary, with some being VERY close together, forming coherent subgroups within the larger overall group. The spacing here is a bit monotonous as it looks pretty much the same between most trunks. Close spacing is difficult to do, particularly with comparatively older trees, but should be a goal--if you can't get trees close together, you're going to have to work the root masses together with selective root and branch pruning.
The subgroups of trees should all have larger "dominant" trees, along with successively smaller trees around it. Although there are some variations in trunk diameter among the trees here, most are the same or at least feel the same.
I'm probably preaching to the choir. You know all of this, but executing on it is not easy. It's alot to keep track of while the trees are on the bench with their roots drying out in the sun. Been there...If I could choose only one thing to concentrate on it would be getting the trees closer together. That can solve the negative space issue as more closely spaced trunks produces more openness in the planting. Also, I completely understand wanting to use spectacular containers for stuff, BUT tempering that feeling with 'what works' makes for better compositions. For instance, using only half of the trees in this pot would make for a better forest...