It could be a combination of your erect posture and a fuller/more muscular chest. I have this issue, which requires me to size up in jacket size in order to have the lapels lay correctly. This, however, results in excess fabric in the shoulder blades since I need extra fabric to cover my chest but do not need it for my back. I end up buying suits to fit my chest and having the tailor take them in at the back seam to try and get a good fit. Despos initially diagnosed the issue for me in a prior thread. From your pictures, could be what you are dealing with.