For a single growing season, I say well done. You said Shohin size, so this is under 8 inches tall from nebari to apex. Nice. Suggestion, you wired every branch, which is good. Some branches you put curves into, but some branches you left dead arrow straight. In a broom there is usually a regular pattern, for example an American elm. Each branch curves in roughly the same arc, or outer branches curve slightly more, central branches curve slightly less to make the crown of the tree. The pattern repeats itself. In your tree you have S shapes, and simple curves, and other variations, without a 'theme' or a unifying structure. The photo, with its harsh shadows show this, probably more dramatically than it appears in person. Which is good. Study your photo, and then plan a more coherent design to the tree. Wire and bend the branches over the winter to the new design, so that you have your theme set when you go to wire the 2016 growth sometime in late summer or early autumn 2016. You want a shape, either a vase shaped canopy, or a flame shaped canopy, or a broad spreading canopy. But there should be a regular pattern, repeated, with each repeat being tighter or looser depending on location in the canopy of the tree. "Fractal" a reiterative design, each iteration of differing dimensions, but repeating the same geometric function. The same forces of nature are acting on all the branches, so the patterns created should have the reiterative shapes.
Draw or do a virtual using this trunk and what you would like to see. Then see if you can get your branches to follow your plan. If the dead arrow straight branches can not be bent, they might be better if reduced to just one internode, and new branches grown to replace them, or they can be removed entirely and replaced if you have other buds coming off the trunk near enough to the removed branches' locations..
Or, go with all the branches being dead arrow straight, and just keep them short, cutting back to one new node each time. This will cause branching at every node. In time age will soften the angularity.
I wager it looks better in person. But use this photo to help refine the tree going forward.
Great growing. Keep it up and this will be a nice shohin in less than 5 years.