I could be mistaken, but I THINK you are at th 3 3/4 line from the top (not the bottom), so I think you are placing it in the right place. Also, it looks to me that you are using the 60 degree ruler with the top tip flattened, if you happen to have the one that is pointed at the top you might find it will work better. I've used both, and the pointed one will cut the fabric so that its easier to match up when sewing the triangles together. Just my two cents on that. :-)