You can test out the shimming suggestion without purchasing the official shimano shims-- just shove something, such as felt, in the gap created when you depress the levers. Floor protectors for furniture legs work well, as they have adhesive on one side. Try them out, then remove if you don't like them. Easy.

I had the dede4girls on my old road bike. They are fairly short reach, but were too narrow for my relatively broad shoulders. I have elf short reach bars on my new bike in a wider size that fits my shoulders and it's much more comfortable. Perhaps measure yourself to see what fits-- you measure from the bump in your shoulder to shoulder while standing up quite straight (this is illustrated on the web-- look for photos). Also note that bar measurements come in two flavors-- center to center (measured from the middle of the bar) and outside to outside (measure from the outside of the bars). The difference tends to be about a cm, so it's important to make sure you know which system is in use.

finally, the arm discomfort you describe could be because your reach is now too short (the reach to the tops or hoods; not the reach to the levers when your hands are on the hoods or drops). This is the most common reason for arm discomfort, per my bike fitter.

Perhaps when you installed the new bars, the reach to the tops or hoods was shortened. If so, you may need a new stem. This happened to me when I installed my new bars, which resulted in a 1 cm shorter reach to the hoods. When I put a new stem in, adding back the 1 cm, my arm discomfort cleared up immediately. Pretty incredible how 1 cm can impact the overall comfort and fit on a bike.

finally, from your pictures, it looks like your hoods are tilted up a bit. This can put pressure on your wrists as well because of the angle that your wrist takes when on the hoods. But the perspective in the photos could be warped

good luck. it sounds like you might benefit from a bike fit, as it seems like multiple factors are in play