Mentor Help?

I became a patient of this person almost more than 2 years ago. I wasn't happy in my career so I decided to change career into nursing. I really admire my np and I told her that when i was no longer her patient. I also asked what her thoughts were regarding a nursing career. Since then I have kept in touch with her (I initiate always) just so I don't lose contact. I really want to develop an informal mentor relationship. I've tried to get together for coffee but the one instance she couldn't and the second intance i didn't get a response. I think I need to tell her my intentions so that she understands why I keep in touch with her and why I wante to meet for lunch/coffee. I want to ask her to be my mentor but I'm scared. I don't know if she thinks i'm crazy and doesn't want to be bothered. what should I do? Should I just email my proposal for her being my mentor? Should I ask one more time to meet for lunch so I can make my proposal? I really want to learn from here!!