It's a lovely dress
But....
Taking in the waist of a circular skirt is almost impossible - if you cut anything away from the top of the skirt it will get bigger not smaller.
If you take in more than a smidge from the back lacing it will loose its shape and impact.
I think the only place you will be able to take it in is at the side seams.
The 'proper' way would be to detatch the waistband from both the skirt and the bodice, take in side seams of bodice and skirt, shorten the waistband then reassemble.
The much easier bodge-job would be to just take it in and accept side seams in the waistband.
Of course it all depends on what the inside is like.