The birth of Gertie's Sweetheart Sundress

My sewing machine is up and running again after moving into our new flat and unpacking my sewing space. It took some time to decide on which project to start with, but since Gertie's new book is out, I though that I wanted to give it a try. There's so many nice patterns in her book and I'm determined to sew through some of them. My favourite is The Wiggle Dress, but I assume it'll require a lot of fitting, and I didn't want to hop into that as my first Gertie-project.

So The Sweetheart Sundress is my first from Gertie's book. I got so inspired by this dress with  red buttons down at the back, and slashed into my black and white gingham fabric that I've had for ages. I didn't reflect on adding seam allowances or not, as it didn't say anything on the pattern pieces. Also, I had read in the book it says (p. 125) that Unless otherwise noted, all the projects in the book are constructed using a 5/8"- (1.5 cm-) wide seam, and regarded that as an advice. I happily added 1.5 cm in the side seams (except the centre back where I added 3 cm in each side to get the overlapping button placket). I was really eager to try it on to see how the fit was...

Something is wrong, and I bet it is the fact that every seam now has 3 cm seam allowance, adding up to 12 cm too many... I am really happy with the front, though, so I will try to remove the seam allowances from the sides only. The back suffers from having too much fabric in the height grain, creating the classic sway back fabric fold, and I will do my best to remove that too. Here's a teaser of how the back will look like: