If you're using a regular Winchester wad, you must be stacking in layers of 2? If you remove the petals from the wad, you stack in 3s. Instant room for 9. A shorter wad, WAA12R (which has been discontinued, but Claybuster makes a clone) with the petals removed gives more room.
What I've been doing id to cut the overpowder piece from a WAA12, then using spacer wads over the plastic OP wad. I cut the spacers from cork sheet, using the brass from a 20 Gaige hull, but commercial spacer wads are available.
DC