if there is such a high chance of her parents rejecting you then why do you have to switch religions? im assuming its more of a tradition than religious beliefs.

your converting sounds more like a technicality because of the family thing. Also just because you dont believe jesus isnt the son of god doesnt mean you are a believer of Islam.

You should probabily start by reading the Koran, im assuming you havent done so, even if you started reading it the first day you met the girl.

You should get to know the girl over these 3-4 years then make a decision about your religion.

you really need to think about this some more before you do anything huge.