Vertically Scrolling Dynamic Sparklines

Hi,

I am currently stuck with my cost dashboard project.

I have a window of vertically scrolling data and would like to add sparklines, showing a 12 month rolling trend next to it. The sparklines should scroll with their respective data. How can I accomplish this with an INDEX formula? I am trying to avoid OFFSET because it is more resource intensive.

Please see attached my workbook. Would appreciate if someone can point me in the right direction.

Thank you!