I think my girlfriend is borderline narcissistic, she needs attentino 24/7, what should I do?

Needing attention? "needing attention" is not enough to make up your mind about a personality disorder. But if it is true, after you do your own research about it, then you have to search your heart. How does she make you feel? How attached to her are you? How would you feel if you stay with her? How would you feel if you walk away? Out the good and the bad in this relationship in a balance and see where it leads.
Think rational. Personality d/o is an ingrained pattern of behavior . In the case of u girlfriend she will be always what she is . U need to ask u self can u live. With someone who only think me.. Me ..
Be very careful! I would let a professional make that diagnosis. There is probably no good way for you to confront her directly. Structure your time to have time for yourself alone. If you are unable to do that and deal with her likely accelerating demands, you can seek counseling yourself to learn how to cope with it and then encourage her to do the same. It's hard to deal with and hard to treat.
You can't diagnose . You can't diagnose her and neither can i. There are many reasons why she need be behaving this way. I agree with the previous answer that you do need to weigh out your feelings, but i think it would also be very helpful for you to recommend that she get a psychiatric and psychological evaluation. It could be something as simple as her suffering from a treatable anxiety disorder.
Narcissist. Therapy for narcissists is often arduous, painful for both patient and therapist, as the narcissist is eventually brought to a place of what is known as profound narcissistic injury, which is the beginning of his poor self esteem that the narcissism resolutely defends against. I would opt for psychoanalysis. She has to want therapy; you cannot force it.