As advised, be evasive. Do what you have to do to remain in the parent's good graces and don't give them any reason to throw you out when you turn 18. (My sister was thrown out, literally when she turned 18, for fornication!)
Any excuse the JW parents have to get rid of someone who is making them look bad to the other robots, er, members of the congregation, they will take and not look back.
I got a job while in high school and used that as an excuse to fade away from going out in Field Service. I also fell back on "Since I'm earning money to pay for the car and college, what do you want me to do? Not go to work? I'm working and learning at the same time. Which is what you encouraged me to do...". This got me out of going door to door and lots of meetings. The logic worked with my Mother, your mileage may vary.
Good luck. Please keep us informed. Clear your browser so they don't know you're on Apostate sites....