The Dutchmans puzzle (?) had me taring my hair out as it came out nowhere near the 12 1/2" it should, so I added a border !
I always hate when that hafpens. Especially when you can't work out why. It looks like you have two different HST sizes - were the sa the same on both sizes? As sometimes that can mess it up, or the dimensions for triangles sometimes are post piecing and don't include the sa! Depends on where you get the directions and how good they are
Happened to me on a hunters star I did. Resized it to 10" block. Cut everything out, thought that's looking a tad small, pieced it and measured it and added a border! Mine didn't include sa so when I resized I lost 2 inches. Still looked nice with she 1" border!
I've never done any that require templates, unless I can draw them on a cereal packet myself, because I refuse to buy the weird shapes that I'll hardly ever use.