Hello,
I have a similar problem with shirts especially, in order to fit my shoulders and arms they end up huge at the waist. Clothes seem to be made with all parts getting larger equally, but that's not how most of us are built. You need to buy 'slim fit' shirts, these are cut in below the chest at the seams. The other solution is getting 'darts' put into shirts by a local tailor, or where i live most drycleaners will do this. They sinch some fabric on both sides at the back giving a better shape. It may be that you have a limited choice where you live. Try online? It always amazes me that in Italy stores carry every single inch size of pants and shorts, shirt collar sizes in 1/4 inches etc, but in UK it always goes in 2 inch steps. No wonder those guys look smart.