Sorry, I thought when you said that she hadn't been open, that that meant she hadn't been baptised.
I think one of the things you would need to work through in marriage preparation would be questions of things that are important to both of your families of origin. If, for example, a big family meal at Eid al-Fitr is part of what her family does, asking her not to do that might be akin to asking someone not to go home for Thanksgiving or Christmas, in terms of the emotions involved. Is that fair and reasonable, and something she is willing to do? Or does she feel that being part of her family means celebrating with them even though she doesn't share the reason for the celebration any more?
Those sorts of things would need to be carefully explored, and both of you would need to be comfortable with where the other was at, for me to think the marriage would be a good idea.