I'm wearing size 5 Huggies Diapers already

I've been wearing Kirkland (Costco) brand size 4 diapers for some time already, but today I've graduated to size 5 Huggies diapers. They are supposedly meant for babies 27lbs and up but for some odd reason, they are smaller than the size 4 Kirklands. See for yourself below. I am the model.