hello verona!
what about you tell your mum that you are doing some light detox so you have a clearer mind when u go back to school???
u could tell her something like you have bfast and lunch but give a break to your system for the rest of the day and thats the reason why you do not eat at night...and arrange for one of your friend at work to enjoy your lunch...there must b a way arround!!!
I think u only need to reasure her that she doesnt have to worry for your health...