There’s no universal measurement for saddles since the “dot” isn’t in a universal place, and even if it was, simply measuring from there to the middle of the cantle doesn’t take into account or flat or deep the seat is, and even in deeper seats it matters if it’s a curvy U, or a U with a flatter middle.
Seats accommodate the butt firstly. For a given flap forwardness, you can go a seat larger to give you a bit more room to sit a bit farther back, but the middle of the seat has to be flatter, not curvier, to do that or you’ll be fighting the curve, unless the middle of the curve puts you back far enough already.
Your height is almost irrelevant, since 2 5’10" people can have very different inseams. It’s the hip to knee length that matters. I’m 5’5" and have not once needed any sort of forward flap, but I have a few shorter friends who fit the same size seat, but need a forward flap because they’re all legs.
And worse, 2 different saddles with the same seat size and shape, can have different degrees of forwardness a their “regular”
It all means - you just have to sit in them. If there’s a specific make and model of saddle that you know doesn’t work for you, and why, then someone might be able to make another suggestion base on the physical differences.