Now here's a topic I can help you with.
I was once a super skinny plain chested model myself... And a reenactment actress! I was 79-59-89 and I wore a hell of alot of corsets. Is all about the design andbeing custom made, yes. I always advice people like you to buy a 17th century inspired corset. Corsets had various variations since then given the beauty standards of each century. The 17th century corset is curve free, usually has a square neckline and the bones usually end in the high waste line (from that line to the hips is just fabric). Run away from those sweetheart necklines: they only fit nice with at least a B cup. Then you can get a waist corset. Those you can get in 18th and 19th century designs and will get your waist really really tiny. I have three of those and although cute they are a bit painful if you have to wear it all day. I can show you some corset designers if you want.