This gave me 144 + 6x2 = 144 + 12 = 156 stitches. It measures 49 cm unblocked and I hope to go to 53cm after washing and blocking.
And here it is what I've managed in about 6 rainy days.
The pattern is easier than I thought. Each side of the butterfly has one yo and one decrease in each row and it's quite obvious where to place them, as the pattern flows in continuous lines.
I am using Addi Lace needles and they are GREAT for the job, with all these twisted stitches. Do not even think of attempting this pattern or anything similar without lace needles.