Thanks so much for sharing this! I also use a pocket notebook because the larger size Bullet Journal is not practical for my work (I’m not really anchored to a desk) and I also tend to forget things if I can’t write them down immediately. I recently moved from two Field Notes in tandem (in almost the exact way you described) to a Field Notes book for my Index, future planning etc. and a pocket Moleskine for my daily use. The Moleskine lets me use the same notebook for between 4-6 months and it is helpful to have to keep track of less notebooks when I trying to find older information. When I was using the two Field Notes books I had a similar passport case to the one you are using. Now that I’m using the Moleskine and a Field Note book I got a different case from Jetpens.com. You can see the style here https://www.jetpens.com/Chic-Sparrow-Classic-Tea-House-Leather-Notebook-Cover-Pocket-Earl-Grey/pd/28576. It is a little bigger than the passport case but still fits in my pocket.
Anyway, thanks for posting. I’ve had a hard time finding other bullet journalists who use the pocket size. It is interesting to see what methods others use that are similar to and different from my own.