I think back to when I was 14 and I reaaaallllly dread my daughter hitting that age. Don't get me wrong I wasn't disrespectful to her face, never in a million years (kids are a little different today though), but I would sneak out and all kinds of sneaky things I thought she'd never find out about. We laugh about it now, I'll say remember when you thought the cat was stuck in your bedroom and I had to kick the door in to get to her (because she was out of town for the weekend) that was really to get your car keyes.
And stuff like that. I can tell you are a great mother and a wonderful person, just stick to your guns and you two will be laughing about it when she's 20.
As far as this cancer shit goes your stronger than that shit so kick the hell outta it!!