Ok... I was a meth user for a year... I did way more than 7 times a day... it is a horribly addicting drug. It is powerful, powerful, powerful. The only way is to force it out of her system. I know she is an adult, so was I... but the only thing that worked was literally locking me in a room and letting it clear my system. I even had to be watched until I no longer wanted it anymore.
As far as tough love... I have mixed feelings. No, you should NOT give her money, but this does not mean she will not find other ways to get it. When I felt that no one cared about me, all the more reason for me to do drugs. No one cared anyway, so what did it matter? Making her feel that no one cares is not the right answer. Meth makes you angry, and her anger will drive her to do MORE drugs. This is NOT what you want. Be firm, but still loving. Tell her you will NOT give her money but if she wants to quit, you will be there for her. Let her know you love her, but don't enable her. She will take you for all you are worth if you give her even a penny. I would not leave her alone in your house though as she will most likely steal from you to get money for drugs. I stole from my own mother... sad, but true. The drug is powerful.
Most importantly know... it is NOT her fault. Her fault for starting the drug, yes, but continuing it, no. Meth is EXTREMELY POWERFUL and it drives you to do things you would never normally do. Trust me when I say that as a mother who gave my one and only son to his horrible father and his 19 year old girlfriend for 4-5 days at a time without seeing him so that I did not have to bother with looking after him. My whole purpose in life was to get more drugs.
The only, only way... is to force it out of her system. I guess you really can't lock her in a room, but if she will allow you to, do it. Be there the whole time as withdrawl from meth is horrible. she will throw up and it will be gross... sometimes like black tar. She will need you to help her through that and make her believe there is a reason to stop. Most drug users start because they feel no one cares, life is pointless, or some other sad reason... don't add to that. Be there for her, but don't enable her. Just be there emotionally, that's all. Give her a reason to quit. Sometimes she needs to hit rock bottom before she will realize it. And all you can do is watch. It's hard, but sometimes that is the only way. Just be there when she's trying to climb out of that hole... my mom was the only way I could have gotten out of it.
Good luck, sorry so long, but meth is a big deal to me as it completely ruined my life. I hope you find some peace and can help her. I know how horrible this is.... any other questions, just ask!