I've always had broad shoulders and never fitted into business shirts / blazers n such. I had stuff tailored, but thats very expensive and still didnt sit nice. What I do now is buy loose, wide shirts and thight, high waist pants. Put the shirt in the pants to have it sit tight around my waist and have enough space for my shoulders to move around. I stay away from blazers, jackets and wear neat sweaters to the office in winters.

Hope this helps. Gg on the gym progess!