Until you are fully in contract in NY, anything goes. If I were the seller, however, and the buyer changed the deal, unless I was in desperate mode I would think twice about staying in a deal with an unpredictable buyer.
It will depend of the details of the contract - I would recommend talking with your Agent ASAP or Attorney to find if any contingencies are in the contract such as: inspection, neighborhood review, septic inspection so you can terminate if you donâ€™t want to move forward with the transaction. Also, ask your Agent to provide a market analysis of the neighborhood to review the solds and revisit how much more you offered. However, this research is usually provided before tendering an offer. Hope this helps.