Firstly, I have never in my life been an XXXL....so the sizing is absurd.  However I am a 12 and I ordered a XXXL and it fit okay.  Its very very cute.  I am a 36DD and there is minimal support due to the halter top, I wish the straps were attached instead.  Also the underwire is incredibly narrow and doesn't fit around my whole boob!  It's really cute and i'm going to sew the straps on and deal with the weird wire.