I am new to chickens and got 3 Golden Buffs. They are 3 weeks old now. I have already decided that I want to get more chickens but would like to get different breeds. Supposedly the Golden Buffs get to be about 4 pounds. What is the size difference between a 4 pound chicken and a 7 pound chicken? I am interested in getting some Speckled Sussex and some other breeds that are 6-7 pounds plus I would love to get some Americanas. I have never seen any of the chickens in person so I don't know what the difference in pounds will look like in size. Thanks.