I think her left shoulder is kind of small as well, (our right, covered by the dagger). And one of her boobs is larger than the other, but I think it may be all perspective.
I also don't get why some artists are drawing things larger as the counterpart, although the counterpart is closer to the viewer. Breasts, arms. The artist did the right thing with the left shoulder (or more the distance between neck to shoulder) and made it shorter. But the result looks like her shoulder and neck are nearly one thing...too close