Believe in Miracles but be vigilent
I will say she has old track marks on the backs of her upper arms and she admitted to using saying she doesn't anymore.
Far more tracks than you saw, especially on the back of her hands, and between her toes.
It would be nothing short of a miracle if she has been able get and stay clean for even a short amount of time. The actions you describe and her attitude are not similar to the Jnessa I met who was stand-offish, solely interest was what she could get out of everyone, constantly lied, ripping off people, drifting from one person's home to another, most often leaving one place because she couldn't pay rent, loosing most of her clothes in the process.
For many people a drug addict who is clean and drinking alcohol is a BIG red flag!! Clean and SOBER has a chance of staying alive. Old timers in AA never realized sober but using amphetamines, stoned every night, many hours every day, was simply substituting other drugs for their drug of choice.
Drug addictions is a nefarious killer. If one looses a stable income the options for effective medical treatment virtually vanishes. Wind up relying on state health care for medical treatment and "rehab" lands one in the cheapest, fast way they can get rid of you while claiming successfully treatment. One of the cheapest ways is to shoot someone up with a detoxing drug and then out the door they go after a week, no counseling. PLOP! Caseworker, if they are lucky, see a Dr for 20 minutes once every 4 weeks, during which the addict is supposed to tell them what they, the addict, is going to focus on, that is to say "Patient Heal Thy Self". If the addict is not able to go to group therapy session at the facility, it is reported that counseling was offered but refused.
Greek Deprived.