I've also tried myself to locate pages for later years for some countries for my own Scott International in order to extend a country a few more years, but I can almost never find what I want. This method solves the problem neatly and cheaply. So I make my own pages and print them onto Scott International blank pages.
I use Bill Steiner's page layouts which you might just be able to print onto your blank pages using your home printer despite their being slightly larger than 8.5 x 11".
https://stampalbums.com/If that doesn't work, print out the pages you need on normal size printer paper and take them to Fedex. Load up the photocopy machine with Scott International blank pages (face down, holes facing out) and print from your newly-printed originals onto your blank album pages one by one. It takes little time and the pages you'll end up with will look entirely professional and very high quality -- and they'll match your album's existing pages.
What about the page borders you may be thinking? If you can't remove the borders on the Steiner pages (and there's a way to do that), you can
(a) Print on the back of your Scott International blank pages. No one will care that there's a border on the back side of each page.
Or you can (b) buy from the seller of the Steiner page layouts blank paper in International album size to use yourself.
Or (c) use a "PDF to Word" program, available free online (there are many available but I use SmallPDF). Load your page file as it instructs you, convert it into a World document (click click click) and then on the resulting Word document, go page by page a select the corner of each page border, then click "enter" and the border will disappear. Print out the resulting borderless pages to print onto your bordered International blank pages at Fedex.