Normally if you accept their counter offer (or any offer) it is binding. You are committed to it and your deposit is not the only thing at risk - you entered into a contract so you could be sued for breach. BUT they haven't accepted??? Weird - so you put in an offer that was open for 1 1/2 weeks? Or they accepted but added a conditon thay they can walk at their liesure?
If you are having second thoughts get to a lawyer pronto - otherwise sit and let time pass and be prepared to move ahead with the deal.
Always work out your offer with your lawyer - your real estate agent - any real estate agent - is not a lawyer or expert by any means.