Right-oh, I just did a quick pec-study by the way of google (finally the adult-filter had some use).. I pretty much have the same issue when I bind. When comparing my pics with the google ones in terms of anatomy there's a few things I figure:
When you bind, either don't push the breasts out, or use tape (best thing I can think of) to strap them down at the sides - which basically sounds like I bad idea since you don't really want tape in the armpit area. Thing is, male chests are broader and the pecs at the sides go down in a steep, straight line - might be able to push the breasts that way but Idk.
Apart from that, perhaps adding another layer beneath the chest will help; less difference in width that way- a curve instead of a hill.
Working out will probably help actually; train the chest muscles (this won't increase cup size but yeah be careful with which ones you train since the underlying muscles might make your chest appear larger - focus on the top/side ones to make your chest appear broader) and probably the upper abs. Training shoulders helps too; broaded shoulder make pecs a bit of a 'go with it'.
Anyhow, that's the best I can come up with at this time.
