Look at you in Pic #2! Muscle definition!!! Of COURSE you can wear sleeveless! So in my crystal ball I predict that soon you will be lamenting about the many manufacturers who cut the armholes so large that you can see half your bra and from one armhole to the other as you lean over.
Before Angie, I, too, avoided wearing sleeveless items for years. Now I run so cold (had warm flashes vs. hot flashes) that they're generally not warm enough for me. Then, I finally figured out that I could always pop a jacket on top, especially the ones that are tight on my heavy arms. Doh!
And I'm hoping that the upper arms don't ONLY get worse! Last October I started to lift free weights in the hopes of getting Michele Obama arms. That may never happen, but I'm stronger and will look better if I'm ever held up, as that is the only time where you can see any muscle definition.