Quoting Destiel:" We live in a house technically owned by my parents, no lease agreement or anything. We pay the full mortgage, ... [snip!] ... contact the companies myself? And does she have a right to control what electrical appliances I use and how much my bill is?"
I think she is upset because you can impact her rating with the company. She shouldn't tell you what appliance to use and she can't control how much your bills are. The thing is that your mom has to realize that you are tennants. Maybe you should put the utilities in your name and mail them to your home. It doesn't matter if the house is a new build or not. You have an address, use it for your mail.