What Can I Do To Help My Failure to Launch Daughter?

I desperately need advice. My daughter, 24, lives in my house and only pays utilities. I don’t live there. I pay for her phone and car insurance. A few years ago, I paid for her CNA classes. She was (and still is) seemingly excited to get her LPN then RN. One step at a time. However, it feels like I’m the only one trying to better her. She’s an CNA and needs to take the TEAS. She said she doesn’t feel confident to take them. I told her to find a way to study, and I’d pay for the study guide. Okay. That’s done. Now her car (which I paid for and pay insurance on) reeks of pot. My house is trashed. She can’t afford, doesn’t make enough enough, to live on her own. I can’t throw my daughter on the street but feel used and frustrated. She lies to me and says someone had a bag of pot in her car and that’s why her car smells of pot. BS. There’s a difference in the smell of a bag of pot being in a car and pot being smoked in a car. I don’t know how to help her. She has 50-50 custody of her son. So far, as far as I know, she hasn’t smoked pot around her son. I’m at my wits end.