They all grow different… so it is pretty hard to judge what would be considered "normal"... they can have gorwing spurts at the oddest times.. ggg
I think you need to judge each pup ..... and me personally, I would rather have a pup just a little over weight if possible... I had an experience with one of my boys years ago and had he not been a rolly polley pup... we would have lost him.. (this was at 4 months).... and he did go to skin and bones...
Also, people need to develope good "eating habits" with their pups... and that mean Do Not Baby them.... If hungry they will eat... IMO they have a certain amount of time to eat and if they don't, it is gone till the next time. One thing that I found and find very, very important is that I know immediately when any of my B's are not feeling well, if they don't eat I know something is up... and that is because they know that when the food is given, it is time to eat... period... ggg... one trick that I have found with puppies is that if you also have an adult (of course I feed in crates) if the pup is not really that interested in eating, I let one of the adults out, open the pups crate door and let the adult help themselves.... you should see how quick the pup catches on...