As a mother, I can say of the two of you you are in far the best position. You have all options open to you that a normal 14 year old has - to have a girlfriend or not, to play sports or join a club, to go to college or become an apprentice, to study the arts or the sciences, to learn an instrument or join the scouts, the world is your oyster.
Not so for your young lady, her options are severely limited. She has, effectively two choices. To do all of those things I've listed (and more)and loose all her friends and family for the rest of her life, or become a 'baptised publisher' - the clue is in the name - effectively a magazine salesman for the Watchtower corporation in order that her loving god will not destroy her in some ghastly way at armaggedon.
The choice is really that stark. I am sorry to be the harbenger of such news. Take your time, (you have all the time in the world as armaggedon is NOT going to happen anytime soon!) perhaps try to establish how commited she is. If she has doubts perhaps you could peruse JW facts.com together. If she is commited you have a problem. But whatever she decides it must be on her own terms and not for you and vice versa, it will only lead to resentment.
Oh & try & focus on working on yourself - educationally, physically, emotionally & artistically. That way you will find happiness from within ( oh and be a better catch for her or whoever rolls along!)
All the very very best Sister D