How do I keep a car that I'm paying for but is under someone elses name?

I have a car whom the loan is under my girlfriends name (and registration). Since I pay for the car payments, insurance, and registration (and the down payment) am I entitled to keep the car if we break up? What happens if she wants the car or tries to take it away from me ? I have proof of paying every single month. Should I get my name on the registration, will that be safe? I don't have sufficient credit to "buy" the car from her but there IS equity on the car. What can I do?