I could be wrong but I believe you ended with a rectangle instead of a square
because you have the order of the fabric attached differently from the usual
log cabin. Usually you sew the two squares then add the third piece of fabric
to those two squares (parallel). Then you keep adding the strips clockwise.
Hope this makes sense.
Here's a tutorial for log cabin. You might also want to number your pieces
so you will know which goes first, second, etc.
https://www.craftsy.com/blog/2015/08...day-log-cabin/