Hi, Sorry I couldn't reply earlier.
First of all, it's impossible to get all images in the photo album in one go. They reflect your personal journey. Not everyone follows the same route, so everyone gets different sets of images.
Image 16-18 and 20-24 can all be found in the alternative "Dolores" ending. You get there if you meet Dolores before you enter the convenience shop, help her with her moped as much as you can, and stay with her in the park until the end. After you are kicked out by Giulia, call Dolores, and the alternative ending starts.
Image 19 can be found if you stay with Giulia, but won't sleep with her in the same bed.
Image 14 is found on Giulia's rooftop. Image 15 in her apartment. They're quite straightforward, so I'm not sure how you missed them.