Here's how I turned the way too small F+F dress into a perfectly fitting garment! After all that trouble I've even learned to like the dress very much, despite the flowery pattern, which it was not supposed to have. I started fixing the dress as soon as I had received the refund from F+F, because I wanted to wear the dress to Tracon9 (which you might have noticed from my earlier Tracon post :3).
Here's the dress before I had begun fixing it.
I started by unstitching the seams below the arms.
Lyckily it was fairly easy to make more slack with this particular design.
Here's the finished upper part, I've managed at least 5cm more around the upper chest!
Here's the back shirring, I had to cut some slack there too to be able to breathe, so I took out some elastic from the sides. I had to unstitch the dress from the neck to get to the shirring between the lining and the overdress and then sew it all back together afterwards.
The mannequin is a bit bigger than me, so the dress is not as perfect in the pictures as I would like. But all in all I think I did a good job with the dress and it turned out to fit me beautifully! I am very happy with it now and I don't think the form or design of the dress suffered any great losses over me tweaking it. I think it was worthwhile to make these changes and I feel very comfortable wearing it now!