This quilt is 62 X 74 inches... a good size for an adult, or older teen..
You say you have 3 yds of the focus fabric
2 yds of red
2 yds of black
If you cut your focus fabric squares 6 inches (NOT 6 1/2")
You will need to cut your strips for the 4 patch 3 1/4" then when you sew the 4 together they should measure 6 inches square. If they are too big, you can either square them up. If they are too small you need to decrease your seams allowances.
Out of your red or black fabric, cut 2 of your inner borders 2inches 50 inches and cut the other 2 borders 2 inches by 62 inches.
cut your inner borders 2 inches wide by the length of the fabric
cut 2 of the outer border 3 inches wide and 66 inches long out of your focus fabric and the other 2 borders, 3 inches wide by 56 inches long.
( I cut the borders longer now, you will be measuring the finished quilt and cutting it then to those measurements)
If you already have cut your blocks, you can piece the borders to these measurements.)
Then cut your blocks for the 4 patch.
You should have enough left of the other 4 patch fabric to make your binding or of the focus fabric.
I am attatching a picture of the quilt using the size blocks you are and the borders the size mentioned here.