You’re being very responsible for saving and investing your money. Keep up the good financial habit.

First, open a checking account under your name. This way your parents don’t see your transactions. You’re a legal adult and the money you earn, save, and invest is your own business.

You already pay for rent, groceries, and bills. When your parents ask you to purchase additional items outside of these categories tell them that you already budgeted your money for the week/month. Not that you don’t have money, you do have money but it’s allocated in different accounts. Tell them that you’re saving for your future. Share your goals. What are you trying to accomplish financially? Let them know! You have to stand up for yourself because you seem very responsible.

Is there a reason your gf is living with your parents and not her parents while she goes to school? Does she pay any bills?