This would be awesome in a little scrapbook, I can picture Ali Edwards all over this! I think they sell "kits" at Michaels and ACMoore, those types of places. You could just add your memories into the blank squares. I would hald-write them so it's more personal (vs. typing). What a great idea!
This and do you have any pictures from when you and your sister were younger. Maybe not specifically pictures associated with the memories but if you were to print out and add pictures to each page with the memories so that she could look at pictures of you as kids too with each memory.