Okay. You may be ahead to use this dress as a pattern from now on. I usually only cut out a pattern once and then do all my adjusting. When I finally get the pattern dress adjusted, I cut out the actual dress material. That way, this experience won't be a waste. I wish you lived closer so I could help more.
When I made Margaret's wedding dress, the pattern was a size 18. Margaret is a big lady (4-5X). I adjusted the pattern adding extra space to what was there. Then I cut it out in a cheep fabric. We adjusted it, took it apart and I used the adjusted pattern in some more cheep fabric. For the final fit dress, I cut the fabric I was using as a lining and stitched it together. I had to adjust the waist just a bit, but then I used the lining fabric to cut the satin out of. Attaching the lining to each piece gave me an actual stitching line to follow. It worked so well I even used the second trial dress pieces to cut out a jacket to go over the short sleeves so she could wear the dress in the temple (she is LDS). Eventually I made her several of these dresses for church, using the same pattern pieces I had created to fit her wedding dress.
Our Walmart sells curtain lining which is white, 90" wide and cotton for !1.00 per yard. I just order it by the bolt. Before Randy died I had made him a new sport coat and dress shirts using this same method. Come to think of it, he never actually wore that sport coat or shirt...