You should split groceries/electricity and all that 50/50. The house is yours so she should not pay for it unless you actually both agree she should pay a monthly rent to live in your house. That to me would be correct. I am in a different situation as you as I bought the house with my wife and even tho I spent more because I had more money available I did not ask her extra money. Also keep in mind that wife is different than girlfriend. So since wife>girlfriend I honestly thing you should get to an agreement with your girlfirend and she should actually pay something for the rent and it should not be all on you.
You should split groceries/electricity and all that 50/50. The house is yours so she should not pay for it unless you actually both agree she should pay a monthly rent to live in your house. That to me would be correct. I am in a different situation as you as I bought the house with my wife and even tho I spent more because I had more money available I did not ask her extra money. Also keep in mind that wife is different than girlfriend. So since wife>girlfriend I honestly thing you should get to an agreement with your girlfirend and she should actually pay something for the rent and it should not be all on you.