What should I do about this?

Speaking as a parent... I would have a problem if you were smoking weed and living in my house. You legally have the right to go, when you are 18 you are legally an adult. Your parents also have the legal right to ask you to move out.

The more respectful you are, the more likely this will go well for you.

I’m having a hard time connecting “senior week” with pot smoking - unless your parents don’t trust you to behave while you are outside thr home.

Assure them that you will follow all rules and especially won’t smoke while on the trip. Try to convince them that you CAN behave.

It’s not about the pot smoking - it’s about you knowing how to act when mommy and daddy aren’t there.

Is behaving something you can do?

If you are unable to abide by the rules of the house as far as I am concerned its "Asta La vista Baby". I would not tolerate it in any way shape or form!