You're right. Amy was a heroin addict, who got tired of being what she was, so she killed herself taking an overdose of heroin. The writer (Adam Duritz) knew her and her group of heroin addicts, and it appeared they all had a common view: "they'd waited so long for someone to take them back home". The line "and some of us sink like a stone waiting for mothers to come" refers to amy who killed herself when she found out there was no way out of the hell she was in the middle of.
You're right. Amy was a heroin addict, who got tired of being what she was, so she killed herself taking an overdose of heroin. The writer (Adam Duritz) knew her and her group of heroin addicts, and it appeared they all had a common view: "they'd waited so long for someone to take them back home". The line "and some of us sink like a stone waiting for mothers to come" refers to amy who killed herself when she found out there was no way out of the hell she was in the middle of.