Will my doctor know I've not been taking BC pill?

I doubt they'll be able to just know, but if I were you I wouldn't lie to my doctor. You need to be as honest about that as possible since things could come up that will require them to know that you stopped. Or, things could be happening that the doctor can't see or know about unless they know you stopped. What could you be afraid of? They're a doctor - they won't or ground you for not taking your pills.