I notice in your sketch on page 1, you say to fold in quarters, connect to make a diamond (well, the inside square), and then move in 1/4" and draw your new square.
In the linked video, Anita draws the 4 quarters first (like you) but then she goes in 1/4" and draws new quartered squares, THEN she connects them to make the diamond.
Will that make a difference?? I *think* that it does. For the video, the diamond tips are 1/4" from the ends of the fabric, right? But with yours, I'm fairly certain it's a little more than a 1/4" from the edge. Since I think (ex-Geometry teacher), yours would actually be .25*1.414 = about .38 (fuzzy math) not .25. I know that's not a lot but I think your way makes it so it's farther in than 1/4
Thoughts?? Response? Am I crazy? :D