Realistically, why does your mother want you? If she is selling her meds, living marginally, got a boyfriend who's at least a pot head if nothing worse, she isn't mommy of the year. Are you receiving some sort of Social Security benefit or something like that, say a payment for being her child while she's on SSI or disability? What does she say when you bring up the idea of going back to live with Cheryl? If you're worth money or benefits to her, if it is of monetary benefit to her to have you, she'll object very strongly. Otherwise, really why not just tell her you'd rather move back in with Cheryl, and why won't she agree to it?