point 1) That figure would not include shorts positions taken on the 29, and 30th the first two days after the most recent high (which were probably heavy short selling days) because those trades were yet to settle (trades take 3 days to settle).
point 2) That figure would not include short positions taken right before and after earnings where there was heavy volume without huge price dislocation (i.e. lots of shorting).
point 3) That low volume short interest and declining short interest corresponds with a recent FB high meaning, this thing doesn't stop going up until nearly all the shorts have covered.
application of points) Short interest is high (probably around 100 million+), volume has been low (probably would take three days to cover), and there are 7 million outstanding feb 16 puts that WS sold and surely wants to close before Friday when they will otherwise have to buy shares for an average price 15% higher than today's close and 25% higher if you think this stock is going to 25 by Friday... surely they won't do this. So, I see a nice short squeeze to 32 starting tomorrow. Good luck with your short.