My cat is small for his age?

My persian cat just turned 5 months old and he is small for his age "weight 2.8 lbs" and the vet checked his heart but didn't find anything wrong with it. 
I know some cats are just small but I want to make sure he is not sick, what should I look for beside the heart? He seems healthy like nothing is wrong, any suggestions?

And would neutering be bad for him with his weight? I'm planing to do it soon.

What have you been feeding him?  How much does he eat per day?

Cats vary widely in size, and nutrition can even exaggerate the differences.  If your vet thinks he's OK, that's about all you can do.
 

As long as your little kitten is happy, healthy, eating, drinking, playing and just acting like a normal kitten, then I would not worry about the small size. Some kitties are really just tiny. What a cutie, I am sure. :rub: Also, your kitten can be neutered. Two pounds or more - no problem. As long as you have a vet that you trust and have complete confidence in, then don't worry yourself. If you are still concerned, you could always take your kitten to another vet for a second opinion. Would love to see pictures if you are willing!