My cat was/is the same way. He was pretty skinny at the time of his diagnosis as well, and he's constantly hungry, even though he's on the path to regulation. He needs to gain weight, so i feed him often. I feed him a whole can of Fancy Feast when I give him his shot, then another 1/2 can (or 1/4 of a 5.5 o. can of something else) somewhere between one and two hours later, and another 1/2 (or 1/4 bigger can) around +3 to +4 after the shot. He has an early nadir, around +4, so I don't feed him much after that. In total, he's getting the equivalent of 4-5 cans of FF every day. He's slowly gaining weight on that amount, though he would eat more if I let him. One thing I'm thankful for is that if his numbers do drop low, I can pretty well count on him eating whatever it takes to bring them up.
Some people have seen their cats' appetites decrease as they get better regulated; I have not, but Mikey has always been a huge chow hound, so I have to cut him off somewhere. I'd say go ahead and add a couple more meals in the first half of each cycle, especially if your furbaby is underweight.