Back to the OP's original question, I haven't come across a single weight/size chart that hasn't had me worried there is something wrong with my dogs... for a second. Then I look at them and know they're ok
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My cocker is at the smaller end of the range for male dogs (he's about 15 Inches high and for his first year and a half he didn't go over about 10.5 Kilos. He is a bit heavier at the moment (12.5 Kilos) and it's too much for him as he's quite light framed, but unfortunately I have a 1 yr old daughter that's sneaking him her dinners
My Weimaraner is VERY difficult to keep at the right weight she's a very big (tall and quite strong boned) bitch but also has an overly deep chest which makes her look like she's carrying a bit of weight sometimes so I cut her food back then within 2 days I can see her hip bones... which is too light obviously.
A dog also needs to be 'fit' and have a good level of muscle to be the right weight and cover their frame also so there are a number of factors that you need to consider - although this will apply less for a younger pup as they don't develop their muscle properly until they are older (over 1yr).
I've just checked Dave's health records and he was 4.6 Kilo's at nearly 3 months but although a small-ish adult, he was a big pup!... so don't get too worried about that. If you're concerned about her weight (forget charts, does she look/feel a bit skinny?) then it's best to pop her along to the vets or back to your breeder for their opinion before tackling it. Hope that helps!