Because I didn't have a corset to take my measurements from, there were a few best guess moments, most particularly in the bustline department... which, surprise surprise, is where I'm having the most trouble!
I had a measurement set of bust 36" (in a sports bra) or 38" (in a regular bra), waist 26", high hip 37". So opted to cut as follows:
1 & 2 - size C, cup D
3-5 - size C to waist, D at hips
6 - size C
The whole thing fits really comfortably, but I've evidently had a few measurement failures and the finished look doesn't quite match up to the comfort level! I can't afford to keep learning from trial and error, so hoping someone can help me figure out where precisely I went wrong?
First issue is the wrinkles around the waist. I used cable ties for the boning, which felt sturdy enough, but I'm wondering if that was the mistake. Or possibly didn't use enough - it seemed too small to warrant extra boning in the panels?
Second issue is the bust, which doesn't feel remotely supported, feels like it starts and ends too low, and leans away slightly at the top. So I'm thinking it needs curving in slightly at the top, but also maybe raising half an inch or so? Except...
The other massive issue is the hideous overhang of fat! Both under the arms and across the back - hard to convey how bad it is in photos, but honestly it looks absolutely disgusting!

So I'm wondering if maybe it's too high on the back? Or not high enough?
I didn't lace it in fully for the pictures (just eaten dinner), but if I lace everything as tight as it'll go, the upper back actually has a far narrower gap than the hips and waist, which leaves me bewildered as to how to resolve the fitting issues.
Having taken measurements with it laced as shown in the pictures, I come out at bust 38", waist 26", high hips 38". Which makes me think I'd do better to try again with a C cup D-C-D sizing next time? Or... am I still getting it wrong?
Also, what to do about the length? I left it at 9" length, though suspect 9½" might be more accurate. Except that still leaves the back issue.
To the (really fuzzy and oddly purple looking) pictures! Sorry for rambling! Hope some of it makes sense and thank you in advance for any guidance you can offer in terms of getting the next one right.