"The body mass index has long been criticized as a flawed indicator of health. A replacement has been gaining support: the body roundness index." Article unfortunately doesn't give the freaking formula for chrissakes; it's "364.2 − 365.5 × √(1 − [waist circumference in centimeters / 2π]2 / [0.5 × height in centimeters]2), according to the formula developed by Thomas et al.10"
Are you sure you've put in your actual waist measurement and not your hips? The 'waist' on most pants nowadays sits at or below the hip line and is therefore gonna be fairly wider than your waist. If you look up a graphic it should make sense
I found a website that said your waist is halfway between your bottom rib and the top of your hip. That was pretty close to my belly button. Got anywhere from 34" to 36" using a metal measuring tape, which could have been part of the issue. But 6'2" with 34" waist should be considered thin, right?