I have a few corsets, and I agree with sprinkles22, the smaller you are, the less reduction you can obtain. Sadly, I like how I looked in a corset better when I was at my highest weight than i do now
(Still have skin flow over in the back of my corset, but now my reduction is a lot smaller). One of my corsets is too big now too (mainly because it has cups and my chest has shrunk considerable....also not too pleased about that...).
I'm looking into buying a new one that flares out at the bottom, I think that may help give the illusion of higher reduction.