How do you determine proportions?

I was just reading your post Are you long-waisted? and though by the test, I seem to be average, I've always thought I had a long waist.
Is it possible that because am tall-ish & thin (5'7" & size 0-2) that
waist-lines fall so high on me - such as designers think that someone my
size is going to be shorter overall? Is torso length a separate
consideration than waist length?

I regularly experience dresses coming to their smallest width a few inches above my natural waist and the hip flaring out over my waist. I've gotten used to belted dresses, coats and robes all tying over the bottom of my ribcage. For this reason I've done empire waists, dresses with flared skirts (where the waist being above my own doesn't really matter), and focused on styles that drape from my shoulders and do not have a waist. I rely on stretch fabrics when I want to accentuate my waist but still have altered all of my fitted dress so the waistline and curve of the hip are shifted downward to fit me properly. I have not worn a one-piece bathing suit since I was a child because when the torso is big enough the suit is far to big around and when the fit around is fine, the suit rides up or flattens my bust.

Also, most of my hip measurement is in my backside, such that I gravitate towards low-cut pants to avoid a weird gap at the small of my back and/or pants sliding downward unattractively. Maybe the low slung pants have just made me think I have a long waist?

There are pictures of me here.

Thank you!