Seems perfectly normal to me! They all grow at slightly different rates.

Our vet has told us that we should go by her parents' weight and that she is going to be big for a female(the males are slightly bigger), apparently her paws are huge but that all puppies grow at different rates. Her mom is like 75 and her Dad is 100 so I guess prob like 80 or something. She told us that you really can't compare puppies to see if one will be bigger than the other because one could be 20 lbs at 12 weeks and 85 lbs at adulthood, while another could be 25 lbs at 12 weeks and only be 65 lbs at adulthood. YOu just never know!!! Its like my brother and I! I was always taller because I grew faster, but then I stopped growing around 7th grade and all of a sudden in 9th grade he shot way past me!!
As long as they are not under or over weight, and they look good, all is well

Right now Kit is barely 13 weeks and weighs about ... 22 lbs I would say. But that is with the accuracy of me weighing myself standing on the crappy home scale with her. She definitely looks lean and "feels like a stone," when you pick her up, as you said about Bentley.

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sounds like your bentley is about a week younger than my Kit.
Krysta