What do I do?! What do I f- n do?! Plz help?

Okay well basically I'm from Iraq. All my long time friends (5yrs) think I'm Italian cuz I was too embarred to tell them the truth.. When I met my girlfriend I told her I'm Italian also bc I didn't expect to fall seriously in love with her but I have and we've been dating for about 2 and half years and I really have been wanting to tell her but I'm afraid of the outcome. She's christian n I'm Muslim and obviously if we get married eventually then religion is going to be a major problem. I want her to convert to Islam so it's okay for us to get married but the prob is that her parents are pushing her to be more involved with church but she tells me that she doesn't really care for church. She's not a bad girl though bc she still upholds to her morals. She knows everything about me down to the very last detail except where im from and my religion. I need to know what to do bc I plan to tell her the complete truth by the end of senior year and before college. Please help me out and please try to understand how hard this is for me.. Iv lied about this since the 3rd grade due to a really bad hazing experience and iv been caring this burden for a long time. We've talked about our futur together and I honestly can't see myself without her and she feels the same. We are both going to the same college couincodentally and same major- medicine. I need to know how to tel her correctly and keep this relationship going and I'm hoping to convince her to convert her when I tellher btw. I'm really thankful for your help...