Fit and Flare turned into Sheath

My dress is fit and flare. I get married in a few months and have had 3 fittings already. As the dress gets altered and tighter, I'm not liking the fit and flare look. I'm short and it's just too puffy for me at the bottom. Unfortunately, it did not look like this when I tried on the sample size due to it being about 10 sizes too big. Is it possible to remove some of the material and turn it into more of a sheath style? Sheath is what I originally was going for. Something fitted the whole way down. I keep seeing forums for a sheath dress altered into something else, but I essentially want the complete opposite! Anyone ever try this with success???????? Help!