A new dress and some fitting help

I've just completed the dress I had written about in my previous post, the one with sleeve ruffles from my latest Japanese sewing book:

I LOVE it! I bought the fabric in a local shop, it's a stretchy polyester/cotton mix, it's very soft and drapes well and above all I was drawn to its silver sheen:

You can't really tell from the pictures but it's super shiny and metallic in real life, I've never had a glittery piece of clothing so that's a nice change from my usual cute animal/any shade of blue makes! Also I wasn't scared of working with this fabric because even though it's soft (ie you must press every single seam or it'll be a puckering mess) I now have a wonderful Janome sewing machine that tackles every project I give it, I feel like I can sew anything with it :) It's one of the cheapest machines of this brand (Facility 21) but it's a really good, sturdy one in comparison with those I used to have (a Brother and a few Singer).
In my last post I also wrote about fitting alterations for some specific problems of mine: as I was getting used to wearing me made clothes I started to notice that my tops and dresses would ride up, with the front neckline getting uncomfortably close to my throat and the shoulder seams ending far behind on my back. These problems come from having a lower rounded back with forward shoulders and a hollow chest, and since it gets worse as you grow older, you won't get rid of these with a few Pilates lessons^^ So, I roamed the internet and beside being relieved to learn that I wasn't particularly deformed since many people seem to have the same problems, I found a few fitting solutions. I tried them and came up with the perfect formula for me:

- I lengthen the back by 1.5 cm thanks to shoulder darts, as shown in these drawings (I cannot find the site/blog where I saw this alteration so I can't link to them but I thank them for saving my life with this technique :)

- I move the back shoulder seam forward by 1 cm at the neckpoint and by 1.5 cm at the shoulder point, removing the same amount from the front shoulder seam and I usually remove 1 to 1.5 cm from the front neckline on the fold:

Of course I also have to alter my sleeve pattern by adding 1.5 to the back and removing the same amount from the front like so:

And that's it, as I said it works perfectly for me but you may want to make a muslin if you want to try these alterations, the amounts I add/remove are quite big because my rounded back and forward shoulders are pronounced but for others even a 0.5 adjustment can make a huge difference!