I'm very proud of you for making what was a very, very tough decision.
You have given her many chances, and warnings, and second chances. You certainly don't want your younger daughter to think what she is doing is OK, and to flout your rules in your own home.
I'm sure that if she ever wants to make changes in her life, you and her dad will be there for her, and THAT is when you can worry about finding the right rehab, etc. Right now it would be a waste of time and money, since she obviously sees nothing wrong with what she is doing.
Many hugs and prayers for you and your family, including Amber.