im also 15 so i know how u feel. my dad also smokes alot of pot but my mom is very against it.. the only difference is that my parents are divorced, and dont talk alot. i think just wait until you get caught, unless they start making it obvious that theyre suspicious like looking at your eyes when u get home or asking alot of questions about where u were and that kinda shit. and when u do tell them , let them know that its just on weekends with friends and ud never think of any other drug. worked for me goodluck