How can I be sure which type of Pomeranian I'm buying?

My mum bought a pomeranian puppy and it was small, cute, and fluffy but soon grew to be one of those long legged, long nosed ones. I don't want one of them atall. I want one of the very short and chubby poms that are very fury and look a bit like teddy bears! How will I know (by looking at the puppy) that it will grow into one of the short guys?? REALLY can't cope with the long legged energetic ones, I just want a snuggle buddy!!