The bus will get you to the port by about 1:30, assuming everyone is at the meet point and there are no traffic issues. The buffets stop serving at 2:15, so you will have time to get on board and go upstairs as soon as you drop your carry on bags. If you miss the buffets, the fast food outlets will still be open.
The "closing" time is the "stop serving" time, not "you have to finish eating and be out of here by..."