I'm pretty sure we're all a little asymmetrical. I have one hip slightly higher than the other (which can be really noticeable in dresses, because on that side my waist is also higher, but for the most part, I'm over it.) That's just one of my oddities. I won't bore everyone with the rest.

You have to kind of wonder if there isn't something just a little off on the jacket for them to be reduced so much. They may fit everyone a little oddly. But I agree-see if it can be fixed and return it if it can't.

Beth Ann may have the answer - maybe it's just the lining!
Love the chevron stripe. I hope a tailor can fix it for you!

I agree that we're all asymmetrical somewhere. I apparently have one ear a little lower than the other, so unless I wear big sunglasses, it looks like I have one eyebrow permanently hiked up. Ha! Fortunately, I like big sunnies.

Una, are you left-handed? If so, you probably have developed your left arm more over time. An old injury to the upper arm or shoulder can also create over-developed muscle in one spot. If you can check the sleeve seam allowance (impossible if the sleeve's lined unless you take the lining seam apart under the arm, unfortunately) you can see whether it might be possible to let out the sleeve enough to make a difference. But that's a hassle, I know, and most garments made now have very little extra seam allowance. Substituting a slightly thinner shoulder pad on the left side might help somewhat, but probably not enough. We all have these body idiosyncrasies that affect fit (mine are a short torso that creates a sort of fold at the mid-back of most fitted jackets & dresses, and one shoulder that's higher than the other.) Sadly, I've learned that the only dependable remedy is patience: you just have to pass up those tempting "almost-fits" and wait. Eventually a jacket with an upper sleeve made for your body will come along.