I would check the average lead time for your market. Most have come down significantly. If the average lead time is 3-4 weeks, then don't worry about what's 6-8+ weeks out, unless your trailing vacancy is poor.
As of right now I am well booked about 10 weeks out, but yesterday I went through my calendar and dropped the price by $15-20 during the odd 2-3 nights windows between longer stays. If nobody books them I don't care, but it would be worthwhile if someone did.
As for your listing, overall looks really nice and has great finishes. I would make a few tweeks:
-Add more art to the walls that have color, preferably beachy colors. You have some nice pop with the cushions on your sofa and beds, so apply that concept elsewhere
-Make sure your art work fits the theme of your area. The buffalo (or long horn cow?) prints look cool and would make sense in the Wyoming but I'm not seeing the connection to Myrtle Beach?
Otherwise, part of what you are experiencing now could simply be seasonality. Summer is over, so I'd expect it to be lean for a while.