There's an alignment error between the cable panels on the back and on the fronts.



Here is how the panels should be placed for the back:

With smaller needles, cast on 83 (89, 95, 101, 107) sts and work 5 rows in ribbing as follows: begin on WS with (k1, p1) 6 (7, 8, 9, 10) times = 12 (14, 16, 18, 20) sts ribbing, 19 sts of the main chart following Row R2, 21 (23, 23, 25, 25) sts in p1, k1 ribbing, 19 sts panel and (p1, k1) 6 (7, 8, 9, 10) times = 12 (14, 16, 18, 20) sts ribbing.



This way the number of stitches between the side and the cable panels will match and all else falls into place.