The EPCOT International Flower & Garden Festival is from March 6 - May 19 in 2013. With both the Beach Club and Yacht Club being EPCOT resorts, I would say that could be why there isn't much availability.
DVC is designed to be fully booked all year round. We are 3 and a half months from your travel dates so it makes sense that there is not much availability left at this point.
You are less than four months from your trip dates. Having nothing avaialble at BCV at four months out is almost a given all year long. Moreover BWV standard or boardwalk view is likely to be gone all year long four months out and and even pool/garden view is gone by that time many times of the year. With DVC, owners at a resort can reserve 11 months out and then owners at another resort can reserve at one they don't own at 7 months out. The result is that most grab anything that might be left at a near park resort shortly into the 7 month out reserving period.