How big should my "oops" fund be when

…I’m disabled, I have a representative payee, I’m effectively unable to hold a job due to medical problems, and my only steady, significant, and reliable source of cash income is $1,346 a month in SSDI benefits? Keep in mind that an “oops” fund should be separate from the kind of emergency fund Clark Howard wants people to have in case of an emergency affecting our banking systems. Also keep in mind that I live with my parents, whom I pay $520 a month in rent. I do receve SNAP benefits.