So I think he is probably eating enough. I will continue to monitor his weight though. We do leave the wet food out all day (well we feed him 2-3 times a day). If there is a lot left in the bowl, I'll add some water and mix it in with new stuff.
As long as he doesn't start losing weight I guess he is eating enough, its as 14+ mentioned, he just gorged when his diet changed. But he's a grazer by nature. And he is also fussy and seems to dislike the food sometimes. He might skip a meal but he will eventually eat when he gets hungry enough. I'm going to pick up a variety of different flavours and brands this time around and see if variety makes him happier
Finally with water, I understand he is getting more water from his food now but he is literally not drinking any water at all from his bowl. Can he get enough from his food? We even tried buying a fountain for him but he wouldn't have any of it.