Laura is correct that the bank will probably counter your offer however it is dependent on the marketplace. There are still some marketplaces in the Washington Metro region that is customary to give more than 3% in closing help assistance from the buyer. This is determined by various factors by the bank and the strongest component is area sales particularly those that ARE NOT DISTRESSED. Check the marketplace for the property you are searching and look at the Fairmarket value homes and see what they are customarily giving for closing cost--most assuredly this is what the bank will offer you perhaps slightly more depending on the condition of the property.
I hope that your loan officer and Realtor primed you for caring for the better majority of your closing cost as this too can be customary in today's marketplace.
All the Best!