Photo vs. Reality

As I'm going deep through my collection by taking their peroforations using perforation gauge even some of them has philatelic bulletin (which has some information including their perforation issued by Pilipinas Philately). But one thing that I found is that my 2019 National Teachers' Month Se-tenant has something wrong, as I go to its philatelic bulletin, I saw 14 for perforation but in my gauge, is not that right. I'm using a paper perforation gauge that was printed and I knew it was accurate, I even used it on one stamp that was really 14 on bulletin, 14 also in my printed paper perforation gauge, but this one is different. As I saw this, I tried to find the real one, I saw 13.7 to 13.9 that fits but my perforation gauge dots were short, my stamp was 3.5 cm x 5 cm (but a se-tenant so 7 cm x 5cm) so it doesn't reach the other point. I don't have an electric perforation gauge so it's harder to tell. Please, contact me if you found any information about it. Thank you