I feel really down.....?

I live at home with my mother and sister.My dad owns a house near by.I am half cast as my dad is muslim and mother a catholic I really want to become a muslim but do not want to hurt my mothers feelings :/ I have had moments to tell her but i just can't do it! i asume she will get a little angry, think i'm doing it because all of my friends are muslims,but truthily im not. i cannot talk to my dad,because well he does not really care.And if i do tell him,he wont do anything about it(thats just him) Shall i wait until im 18 and convert? but i always fell down,kind of depressed.