Here is a new schedule for 13 rounds.
(F C) (H D) (E G)
(A G) (D B) (F H)
(D E) (H C) (F B)
(A B) (H E) (G D)
(C B) (H A) (F E)
(F D) (A E) (C G)
(H G) (F B) (A D)
(E B) (F G) (A C)
(C E) (D G) (H B)
(B G) (F A) (D C)
(F G) (C B) (H E)
(H D) (E C) (B A)
(H A) (G E) (F C)
As you mention, not everyone will play each other twice, but note that as you don't have a multiple of 4 rounds, then the number of games is also unbalanced - above players A and D have one less game than all the others.
Ian.