[autumn star]

I am sorry to say that I would have to agree w/the others. If you are going to be gone for an extended period of time it would be very unfair to any dog, not just a yorkie.
I think it would be very hard on your pup as well - going from a home where there is someone around often to being left unattended for hours on end. I know it is hard to hear because I am sure you love your pup but your mom is right.
Maybe you could get a cat. (not that a cat would replace your yorkie) so you would have some company.
You never know if your life settles down a bit maybe your mom would be willing to give the dog to you then or maybe when you have more time to give a pup you could get another one on your own and then you and your mom will have something in common and the dogs can have a forever friend.