I have a black pom. and she is not fluffy either. That is because she doesn,t have a full undercoat. That does,t mean they are not a full blooded pom.
I breed pomeranians , poms get there full coats any were between 1 to 3 years old , yes some poms have taken up to 3 years to get a really good coat, so give it at least 3 years and yes they can have a bad coat and be pure bread.