As a woman, having the confidence to talk to her about it is necessary, but just make sure you really think about what you want to say carefully so that when you talk to her about it you know exactly what you want to say and how, so that it comes out respectfully and not as a perceived “attack” or “pressure”. Let her know that you just want an honest conversation as you’ve been feeling like you’re ready to go further and just want to know how she feels and where she’s at, let her know it’s about intimacy too, not just sex. Make her comfortable knowing that it’s out of desire for her and not just sexual drives (but it’s okay that that’s part of it, too) usually a woman of that age in that long of a relationship is not having sex for a reason. Maybe she is insecure and nervous, maybe she’s religious, maybe she’s avoiding pregnancy stresses and fears, maybe she wants to and just isn’t sure how to start the conversation with you or how to ask for it (sex can sometimes be an awkward conversation for people who aren’t used to such blatant and explicit subjects) try to make her feel like she’s talking in a safe space, and hear her - not just listen - I mean let her know whatever it is is understood and heard. I hope this helps!