I think width depends on comfort. I am your same height and many years I used a 40 cm handlebar, but last year I got a new bike that had a 42 cms handlebar and I was surprised about comfort and safety, then got a new 44 cms handlebar for other road bike and noticed the error I was in, for many years, this is my width. I am a 38 cms shoulder and the rule to follow doesn't worked in me. I really feel good with this 44
, although it doesn't represent any danger to other riders, they dont see your handlebar. Even new handlebars are flat in the upper area and really helps in staying safe. Regards