Good advice here.
Boundaries.... man, are they hard!!
Looking back, I often thought - "whew, thank God it's only pot and not meth" ...derrrrr. Why do I think it would be different for my kid than for me? If I drink a beer, and then on another day drink two, and then on the weekend decide I might like just one more - you can bet your bottom dollar I'll be back to swiggin' rum and coke and sleepin with dogs in no time. I KNOW that. I've been sober for 25 years, I don't need to test the boundaries because I already did, and lost.
My kid is like yours - she is young, she has done a few rehabs and is currently doing a ... ahem... "county" long-term intensive inpatient (read: JAIL!) for the next few months.
What I know is that if she is still digging to find her bottom there is not ONE WORD I can say that will get her sober. Not one.
Because of that, when my kid is out, sober and the best person in the world, I have to say "no" to her living with us. I hate that, but we've done it enough to know that having a front row seat to relapse is almost more painful than anything else!
Nineteen is a fine age to be out on your own - I did it at 17, as did many of my peers. We found apartments, jobs and cheap apartments. Kids today want to have their own bathrooms, cell phones, cars and gas AND nice house... because that is what WE give them. One of the tough lessons I've had to remember was just how proud I was when I was able to do it on my own. Who am I to take that away from my kid?
My son is a pot addict, age 25, currently sofa surfing and not working - can't pass a pee test.
My daughter's first time living alone is in jail, she is a meth addict... and currently suffering from meth-induced psychosis, which gets a little better every week, I think.
I cannot save either one. They have addiction, and they need to deal with it. Each time I've tried to make it a little easier on them - by buying them cars (yep, several actually), paying for rent (many times), helping with the heat, the lights, the garbage, money owed to a dealer (can't believe I did that - once). Each time I helped, I stopped their fall to their bottom.... each time.
I cannot do that anymore. Financially, I am broken. Emotionally, dried up. Intellectually, finally "getting it". My kids are now adults and to BE adults means having experiences, some painful, that teach us how to live in the world.
So I go to my meetings, watch how others are doing it, got a sponsor and am working the steps (again) on me! What a change from just a few short years ago.
I believe in a power greater than me.... and greater than addiction and big enough to hold my kids and give them what they need.
I wish you well. ((hugs))