Hi Querida,
12 days will be very tight to see much at all, because many good anchorages require some fairly big side tracks where you will easily loose days getting in and out, as well as the days it takes to explore them. Tides will also govern and slow your progress in and out of anchorages. But here’s a few I can recommend that aren’t too far off your route.
King George River. (Can only get in and out at high tide)
Freshwater Bay
Rainforest Ravine
Hanover Bay
Deception Bay
Silver Gull Creek
Coppermine Creek