Do you look thinner at a certian weight compared to your youth at that weight?

Without looking at the size number on clothing labels, I think you are absolutely right.  Part of this has to do with the fact that when you are younger you have more muscle mass and bone density and also as important more collagen in your skin.  When you are older, the collagen starts depleting in the skin, so it isn't as plump and firm to the touch and that is one reason why skin can sag, not just from losing excess weight quickly.  Even someone around 33 bmi losing down to 19 bmi, is going to see this type of change just due to these factors that occur with being older.