Hey Icy42,
I understand the horror that is puberty for you, and the need to stop development as a boy. But I think it is important to remember that even if you had to wait till 18 you still have a fantastic chance of getting great results.
My advice is to keep chipping away at your folks. Ask them for the chance to see a councillor or therapist, keep at it. Don't stop till you find someone that listens, don't stop even if the councillor backs your dads view (sometimes happens). Keep asking for help and eventually you will get some. It was a good sign that your mum was happy you shared with her, it shows that she is at least open to talking about it. Take heart from this. Talk to her about your feelings, your pain. Let her in on your world. Often people don't understand the agony it is to be transgendered and that it is not a choice. Don't just do it once, keep at it. Give them information about being transgendered, help to educate them.
Good Journey.