I think your on point layout is probably right, it explains everything, including the triangles. She probably lost a block. You could make a substitute one for the missing one. She used many different blues, you could probably get pretty close.
Here's a layout that uses 17 blocks.
|XXX|
XXXX
|XXX|
XXXX
|XXX|
|-note this is just a spacer
If you make it a row of 3, row of 4, row of 3, row of 4, row of 3 it makes 17 blocks, you offset the short rows HALF a block.
It doesn't accommodate the setting triangles, tho.
It's sweet of you to finish this up for her.