Start Loop&Merge on a selected loop based on previous selected choice

What do I want to archive?
I would like to implement a staircase procedure. I have 11 images of abstract shapes, that vary in the amount of curvature introduced in the shape. The variations go from 1=maximum curved to 11=maximum angular. I will ask people: is the shape curved? There is no right or wrong answer, and I am interested in measuring the subjective threshold for each person, e.g. some people might say that image 5 is angular while someone will say it at image 8. Once they answer ‘angular’, I want them to proceed backward: e.g. if my participant says ‘angular’ at the image 8, I want them to then see image 7, not 9. And I want to repeat this for three times.
The ideal scenario:
The ideal way of doing this would be with a 2 blocks, one with a Loop&Merge Field that shows images in ascending order (from 1 to 11) and another one that shows them in descending order (from 11 to 1). The problem here is that I would want people to start the block in descending order based on the question they provided in block 1: e.g. participant says that image 1 to 4 is curved, but image 5 is angular. Then I will skip to the end of block1 and I ideally I would want block 2 to start from image 4 and proceed in descending order (3, 2, 1). This until the participant says that the image is curved again. In this case, I will go back to showing the images in ascending order: e.g. participant says that 3 is curved, then the next image should be 4, 5, 6... and so on.
What have I done?
In the second block, I created 11 Loop&Merge fields, each starting from each of the 11 numbers in descending order (see below). I also added a display logic, so that if participants answered ‘angular’ to image 8 at block1, they will be redirected to the question that displays field7, with image 7 in block 2.
The problem with this is that I will have a series of empty rows that will make the Loop&Merge impractical, as for example field5 will have 5 empty rows, that will not have an image to show to participants!
Question:
Is there a way I could make Loop&Merge start from a selected row based on the answer they gave in a previous question? Or is there a way I could skip blank rows? Could embedded data be playing a role in this?
I could not find anything like this in the Forum, so any help would be much appreciated.
Thank you guys!