I am married to a non-Catholic, a prince of a man who fully cooperated in raising our boys Catholic and accomodating himself to my practice of the faith but who did not convert (at least not yet).
That was hard enough, because he is always, to some extent, on the outside looking in. That’s hard. If this is important enough to you that it is even on your radar–and thank goodness you realize that now, and not later when you have a child in your arms you realize you just have to get baptized–let your girlfriend find someone who will be happy with her just as she is. That is what you ought to want for someone you love, friend. I would not ask her to change herself. If she goes off and changes her stance towards the faith on its own merits, fine. Don’t make this into an ultimatuum.
As for you, find someone who also finds what is so important to you is also important to her. She doesn’t have to be Catholic, although that is the least difficult. She does need to be fully supportive of something this important to you. Besides, if you marry in the Church, the priest will be making certain she knows you have a positive duty to raise your children Catholic–and you do have that duty. That is their birthright.
I had a friend who used to quip: “I tell these young ones, don’t marry for money! Hang around with rich people, and marry for love!”
I’d advise you to do the same. Socialize with other Catholics. Practice your faith seriously, as you intend you will when you are raising your children Catholic. Don’t hide it. Live it. Be open about it. If you don’t marry a Catholic, you’re at least likely to marry somebody who is open to the faith. Better yet: make it clear early on that you need that, because you don’t think it is fair to your children to have this be a point of contention with your wife. I hope you see that is the absolute truth.