Well unless you're lying about your age, it's gonna be harder for her to accept you because of your age. But you shouldn't try to do everything to please her. You have to say no sometimes or she's just gonna walk all over you. But you should try just being her friend at first. Like go to the movies or dinner. The rest will come eventually.
I'm guessing she's resenting you but that its for her father to sort out. You've done all you can by the sound of it. I'd be pushing him to organise some time together just the pair of them, but that's me.