You are working at so many cross purposes here, I don't know where to begin.
First off, quit with the trunk painting with lime sulfur. It makes maples look extremely weird and can lead to soil issues with the quantities used. Also such detail work is usually left until the tree is "completed."
The trunks your are working with will not produce the tree you're aiming at. They're both the same caliper and will stay that way unless you drastically shorten one to mask the similar diameters. That's what happened to your model tree. One trunk dominates the other. With yours both are equal (and boring). Choose one as the primary, chop the other by at LEAST half, two third would be better.
While you're doing that, get the tree out of the pot and into the ground (assuming this species can be grown as a landscape plant in your area). You are looking for substantial growth to bulk up leaders and develop the canopy. Development time for that can be halved if this is in the ground and not in a pot.