Ralphie is almost 21 weeks, he weighs 8.4kg, should i be concerned about his weight just yet?? he's always been quite a largeish pup and i've asked the nurse at the vet clinic her opinion and she felt that he was ok but that was a few weeks ago. I've looked at body scoring but dont know whether this really applies to a puppy, i don't want to let him become overweight but also i don't want to underfeed him.

he eats twice a day now, approx 150g of Iams puppy in two meals(the package states to give 230g daily for a dog that will be approx 8kg as an adult but i think anymore and he might just explode!!), he has no snacks or left overs, any treats are low fat or chopped carrots