Switch if you feel like your agent is not aggressively marketing the property. Also, find out what the typical days-on-market is, as well as the amount of inventory. If you already know those, would you share them with us?
For example, in my (larger) midwestern city, even in January, DOM average is like 10 days, and many homes are going in 24 hours. Our inventory is only 3 1/2 months whereas it's normally 6 months. So definitely a seller's market here, and if our house would have sat for a few months, then yes I would probably blame my agent, at least for not communicating the problems with pricing/condition.
And yes, your contract might have an extension for any sales that take place after the contract expires, IF the buyer was someone who saw the house while your original contract with the agent was in place. Read it and see!