Packing Woes

So the trouble we've run into now is giving an estimate of weight and volume of the stuff we'll be shipping.  Um, my dishes are still in the cupboard, and I'm certain our bed won't fit on our bathroom scale.  I understand that they need to know the size container that we need, but how in the world do they presume we tell them when this is not something we do regularly?  I don't stand around guessing the weight of my things, or how many boxes (and what size) it would take to pack up an entire room in my house.  When this is all said and done, I certainly hope I can give some hindsight to this issue so some of you out there will not have steam coming out your ears as I do at this very moment...