How about the following schedule?
(G N) (C L) (D K) (I J) (B E) (- -)
(H I) (D J) (A B) (E F) (- -) (M O)
(G L) (F N) (C E) (- -) (K O) (B J)
(L M) (F O) (D G) (C H) (I N) (A E)
(B O) (H K) (F M) (A G) (J L) (D E)
(E H) (A O) (J K) (M N) (C F) (I L)
(F J) (D L) (A I) (G H) (E K) (B N)
(A K) (E G) (F H) (B I) (L O) (C M)
(B C) (A H) (J N) (F K) (D M) (I O)
(D N) (I M) (A C) (E L) (H J) (G O)
(F I) (G J) (E M) (C N) (B K) (D H)
(G K) (B F) (L N) (J O) (C D) (A M)
(J M) (K L) (E I) (D O) (C G) (H N)
(H L) (E N) (B G) (K M) (D F) (A J)
(B D) (I K) (C O) (A L) (H M) (F G)
(A D) (E J) (B L) (N O) (G I) (C K)
(C J) (B M) (H O) (D I) (A N) (F L)
(E O) (C I) (G M) (B H) (A F) (K N)
Where one of the sheets is unused in each of the first three weeks. Each team plays 2 or three times on each sheet. There are 18 rounds in total with each team having 4 bye rounds, no team has two byes in a row.
Hope that helps.