I have cruised with my 10 month old granddaughter, who was also in between table and baby food. We brought some baby food (those available in plastic), but she ended up eating mostly table food. The waiter brought her a plate of broccoli, pasta with cheese, and a fruit plate every night. Her food came out before ours did, keeping her happy and eating nutritious food first while she was hungry. She then was given her fruit and bits of bread while the adults ate. The pre-packaged baby food was good to have for shore excursions.
I would have no problem using the ship's tap water to mix formula. If the refrigerator in your cabin is not cold enough, put some ice in a small bowl or large cup in which to store food or a bottle of mixed formula. Stored in the refrigerator, the ice will last quite a while and you don't need to wonder, if the temp in the frig is cold enough.