The 4 cut outs on the top and bottom are sewn together to create a corner, now the sides are taking shape.
The pink lines are the sides of the piece and showing the base. Sew the pink lines together where the end of the zip will be. Side seams sewn.
Open it up and place the now sewn piece and line it up onto the base part and sew.
Repeat on the other side. The basic shape is happening.
Insert the zips from the centre front down the sides
Almost there, this is where the bag takes shape. From the top corner to the base corner, fold and sew down using a very narrow margin, this creates a mock seam. Do that for all the seams,
Place webbing for handles, this is the view from the base. I have not sewn it on as I know how I want it on the real bag. It is only there for measurements.
This is the view from the top of the bag.
On the real thing it would have fat 1/4s and a plastic window, (I don't have fat 1/4s, so mine had wool in it). It shows on the bag where the plastic pocket will go.
This is my pattern diagram, I hope it makes sense!