I just picked up my dress this week. It's a gorgeous dress, as you can see in the pics below. But I am realizing that I am going to need MAJOR alterations. The dress is very low in the back and after trying on many, many different bra types with it (strapless, strapless corset-style, convertable bra, regular bra altered with lowering straps, no bra, silicone adhesive bra, boob tape) I've found that I cannot wear this dress without a regular bra. I am a 36G , 5'11", and I am 40 years old, btw, if that paints you a better picture. I am going to have to have the back raised somehow.
I have an alterations appointment scheduled for August 19. My wedding is September 13. I am terrified of what the seamstress is going to tell me when she sees this dress and what I need done to it. It's a 2 layer dress with a satin spaghetti strap underlay (and oh my does that material show every pucker). The satin underlay cannot just be raised by shortening the straps because that would raise the hem of the dress. The only thing I can think of is if the train fabric were to be cut off and used as extra fabric to be sewn on to the top somehow (I was going to have the train cut off anyway). Looking at the dress - in my admittedly panicked mind - this seems inconceivable.
I don't know what is and isn't possible to be done to a wedding dress and I am really scared. The back is not the only thing I need altered. It was purposely ordered in a larger size in order to be altered down, so the waist has to be brought in as well as the thigh area to bring it back to the mermaid style it's supposed to be. I've tried calling the seamstress to explain my situation but she is on vacation until the 11th.
I'm asking any seamstresses out there or anyone who has had major dress alterations to please offer me suggestions or advice on what my options might be. I don't care what the cost is. I would be willing to go to extremes like change out the underlay completely, change the underlay into a skirt and add a different top part underneath, or whatever else anyone can come up with 
Thank you in advance for your help.
-Melissa
.