Honest opinion, if one of your younger sister's friend's parents were feeding that friend steroids and your?

First I must state that YOU sound very intelligent. I commend you for wanting to get some help for this situation. However, it does upset me to hear that no one in your sisters school makes you feel comfortable enough to go to them for any situation, for the fact that it IS a Catholic school even more so. You should indeed call that child's help hot line, they do not ask names. Or you could call SRS and they could look into the situation. You didn't mention anything about your own school, so how about trying to speak with a counselor there. SOMEONE will eventually believe you. You say you "feel responsible knowing this information", but don't stress yourself over it to much because you can not be responsible for everyone else's irresponsibility!