I am 5'4" tall, 120lbs, wear a 32DD bra, and size 4 in pants.  I ordered this in a medium and, remarkably, both pieces fit!  I ordered this primarily for the top, so the bottoms fitting was just a bonus, since I doubt I'll wear them.  The coverage is fine from right to left, but they are a little too low rise for my taste, my crack is just barely covered in the back.