mine had none either when i bought it.Hello Papart. I agree with others that your back bone is quite good. I also see an excellent balance between positive and negative space, with really good spacing of your scroll elements.
The areas that need work are the detail of the elements themselves, and with such an excellent sense of space and proportion, with the right resources at your disposal, I think you'll have little difficulty refining the individual scroll components as well.
With all deference to the excellent books available, speaking only for myself, I tend to learn more quickly and efficiently from hands on instruction. From seeing and doing.
One of the best (and it turns out smartest) things I did when I started this Journey was to purchase Sam Alfano's excellent guide to drawing scrolls. You can find the video for purchase here: https://masterengraver.tv
I believe there's a DVD available as well, but since my MacBook doesn't have a DVD drive (quickly going the way of the dinosaur), I opted for the downloadable version with free video player. This also turned out to be a smart choice, since I can play the videos anytime I want on my laptop or iPad, without an upcharge for using the videos on whatever device I'm using at the time.
Note: The scroll drawing video came first, and the iPad several months later. If you choose to purchase the video, and I hope you will, all you really need to get started is a clean sheet of paper, and a humble #2 pencil.