Worried that my dress is too form fitting

Had my first fitting a couple weeks ago and my second fitting is in a week. My dress will be taken in at the waist and thighs giving it more of a form fitting mermaid look though my dress is labeled as a sheath. I’m worried it will be too form fitting making my booty look “voluptuous” and I’m feeling self conscious about it. It didn’t feel tight wearing it but in the pictures I took, it looks tighter than it feels. The seamstress said that they always leave some extra fabric in case it needs to be taken out...but I feel so anxious because I don’t want it to be ruined. Has anyone experienced “taking out” a dress??? I’m trying to not think about it too much and just wait until the second fitting but ughhh I just wish I had it taken in a little less. I also think the bustle brings attention to my butt because it’s pinned right under it. I just need to vent...