Here is how I would do the sewing and joining. Starting with your first hexi to the left, sew 6 strips all around. The next hexi, sew 5 strips and then join it to the first hexi where you havnet added the strip on that side. Continue this way until your row is done.
This is where it gets a little complicated but bear with me. Assuming this is your top row, the second row you would sew only 4 strips on the first hexi leaving the two top sides alone. The following hexis you'll sew 3 strips (right side and 2 bottoms) and sew that second one to the first and continue on.
You'll have empty spaces at the end of these rows (row 2,4,6,etc) . You'll either add a half hexi or a set in blank hexi to fill the space.
I hope this makes sense. I see it in my head but not sure if I'm explaining it well without making a quilt myself and showing pictures of the steps. I'm sure you can figure it out.