Not sure what "last week" means, but you should have heard something within a day or two. Having both bought and sold via resale, I can tell you there is really no reason for an extended delay. If it's been more than two days, I'd call the broker and ask them what's going on.
If there has been no response from the seller, I'd look for another contract. If you find another contract you like, cancel your offer and make an offer on the new contract.
I'd also check with multiple brokers. Some brokers are more conscientious than others about getting answers and getting deals done.