Ethereal, I think a boyfriend blazer would be very difficult to pull off with the body type you described. Even though the modern version has mostly softened the prominent shoulders and boxy tailoring since the last time this trend was big, the shoulders still feature prominently, and the tailoring still has a strong, imposing silhouette; both things that are doubly emphasized on your body type.
I am slightly t-shaped (shoulders broader than hips), imo not enough for it to be considered a flaw. But a boyfriend blazer makes me
too t-shaped, plus it obscures and disrupts the fluid slopes of my natural outline. I wouldn't describe the effect as
butch, rather, as a cut that renders my look too somber and, er, asexual.
I look at so many girls on the street and celebs/models looking amazing in bf-b's. But for a blazer to look good on me, it must have a more feminine style; perhaps a slight princess sleeve, daintier collar/lapels, curving in at the waist, etc. In short,
not a boyfriend style.
You mentioned you don't like frilly stuff, so a 'feminine' blazer like the one I described might not be to your liking. So I highly recommend a kimono-inspired blazer for a similar effect to the bf-b. Because these have structure and sleekness, are
not frilly or dainty, but they have a very flattering cut that would soften your body type. Imo, it's also just a really a beautiful style, much nicer than boyfriend blazers. Some examples, as there are both subtle and more direct takes on this design:
etsy.com (Found via google, can't credit the seller)
nyandcompany.com
same as above
shopbop.com
Hope this was helpful, let us know how your styling goes
