A little backstory.. I never saw myself wearing a mermaid/trumpet style dress, but when my mother-in-law asked to see just one on when I went dress shopping, I fell in love! The dress (on the right) was a size too small at the time, so I bought the next size they had available (which was two sizes too big)... I have lost roughly 13 pound since then (as you can tell by my chubby face in the right photo) and my seamstress has to take the dress down four sizes on the top and two in the waist... Now, my dress is still undergoing alterations, but I am suppose to have what I thought would be my last fitting this Saturday.. As I looked back on photos from my appt two weeks ago, I kept thinking something seemed off with the bottom of the dress.. My FMIL has said at two alterations appts now that the dress needs to be taken in more at the hips and below, but the seamstress is saying that the material is not stretchable (it's satin) and that I won't be able to sit down. After relooking at photos and finding the photo from when I said yes to my dress, I am thinking my FMIL is right and that the dress needs to come in more to prevent it from looking like it is just hanging there.. Below is a side by side of the two and the dress on the model.. Looking for advice/opinions! This has literally kept me up all night! Haha!
Left Side: After Alterations ---- Right Side: When I picked my dress 
How it looks on the model 