I'm very unclear here about whether you have your own agent or not. Generally, if you back out of a deal after the initial 17 day inspection, you will forfeit your deposit,
If however, the seller is unable to sell in the time period you agreed upon in writing, you should be able to cancel.
That said, I would need to see your purchase contract and escrow papers to know exactly what you're dealing with.
If you don't have your own buyer's agent, I encourage you to consult with a real estate attorney.