sorry there is no washington inmassachusettssorrythere is also no greyhound STATION in New york there is PABT thought but itsfor all carriers not just greyhoundaslo note there several other bus companies that operate same routemega bus, bolt, washinton-nyc expressssome of those might pick up in queens which is closer to JFK
The bus terminal is called The Port Authority ;It s at 8th Av 42nd St in ManhattanThe best way to get there w/o only a single carry-on luggageis:Take the AirTrain from JFK to Jamaica Station and as you exit pay $5.00 for the Airtrain and $ 2.25 for MetroCard which will get you on the E Train to the Port Authority Subway cars and subway station are not designed to accommodate people w /lots of luggage and while getting a seat on the E will be easy exiting it w/ luggage onto a crowded subway platform will notIn that case spend the extra money and take the Long Island Rail Road Jamaica to Penn Station Manhattan , exit on 8th ave and just walk the 7-7/20 mi- blocks to the PA