Short sales take very long times.
I have short sale buyers waiting for 9 months. It depends on the negotiator, but sometimes the negotiator cannot do much if the bank negotiator doesn't have time to talk with the seller's negotiator.
The good news is, I suddenly have so many long waited short sales approved. Seems the banks are accelerating the process.
I don't think you can do much about it. If I were you, I would start looking at other properties. If I can find a better deal and can be closed, then drop this one.