Question about a thin kitten...

Kairi is growing fast! He was 1.4 pounds last week he's now 2.3. He's really thin and doesn't seem to eat all that much. I can feel his ribs, but don't think I'd be able to see them clearly even if he was a DSH. I can also feel his hip bones, and I was just wondering (since I've never had a kitten, and it's been a long time since being around a kitten) if this is normal?

He plays like crazy, jumping around like a june bug until he drops in a kitten like tired crash. He's drinking water well, but only eats a couple of bites of food here and there, but comes running for his vitamins and a pounce or two during the day.

I read about all the things that can go wrong and I'm just a nervous Nelly.

Kittens grow quickly and it can take some time for them to put some meat on their bones. What are you feeding him, how much and how often?

I figured it was probably a growth thing. My kids get chubby then shoot up, and look emaciated.

He has moistened Blue Buffalo all day as much as he wants, then a half to 3/4 of a can of premium wet, he's a little finicky about the canned, so I've been trying several and writing down what he likes. None of the blue buffalo canned is to his taste. But he goes to the bathroom all day, good solid poops and an appropriate amount of pee.

I'm thinking I'm just a nervous kitten mama.