I don't have the pattern but I think I know where you went wrong.
In step 1, your sewing the two edges of the right sides together of the outer fabric.
In step 2, your doing the same thing to the lining fabric, but skipping the open section on the side.
In step 3, layer these, one inside the other, with right sides together. Match up the unfinished edges and stitch around the top of them. I'm pretty sure this is where things got out of wack for you. If it still doesn't work for you, let me know.