Apart from the skipped page as @H1dd3nM4st3r said, instead of the original 2000x3000 images you used the 1280x1800 resized ones that you can view in the galleries here, and that are scraped by aggregator sites like e.g. NH-dot-net that seems to have all the mindshare lately. Galleries are usually uploaded here first, other sites repost the okay-quality version that's only really suited for viewing but not for editing (because having been created at 80% quality there are noticeable compression artifacts, besides the smaller size making your job harder than it needs to be).
Full-sized images are available from: 1) Torrents - if still seeded, usually that's the case for stuff released in the past few months; just avoid those with 1280x in the name as they're for the downscaled version 2) Archive Download link - Choose "Original Archive", may cost some GP depending on your level, stars, how old is the gallery etc. 3) Page by page, by using the link under each image that reads "Download original source" (if there's no such link, the image displayed for that particular page is already the original size).