Out of toilet paper. That is when you know.

One of the 1st markers to indicate you are an adult now. Running out of toilet paper. Thats right.
Unless you have a great roomamte or hyper responsible dormmate. You will run out of toilet paper beacause your parents aren't there to buy it for you.

Another is cough medicine, "mom always managed to have some around" she does live at your house.

You are an adult now so all those things are your responsibility.

It is those silly little household things that told me [rather hit me in the face] that I was on my own.