Happened to me as well. I was actually friends with her dad first (sports), which is how she got to know me. She was hot, flirty and everything I was looking for....and so I was asking the same questions you are now....
Dated her for about a year...it was great. I didn't see her all the time (she lived on her own across town), but the arrangement worked well enough. I eventually broke up with her when I realized she was looking for a sugar daddy. I still saw her on occasion when I felt like getting laid - best kisser I ever knew. Problem was, she would look me up at inopportune times - be sitting in the parking lot of where I worked (she'd get out to meet me, not covert or nothing), leave notes (even left a rubber once) under my windshield wipers so I knew she had been there, but it was creepy. Never know where else she's going to want to suprise you. Sure, in a way I was flattered, but you never know what's REALLY going through her head. She even popped up one time after not seeing her in FIVE years (at work - same place). Did it get old? Not really, there was no effort whatsoever on my part to keep her.
.......and there was a nice upside; other girls tried to figure out why this chick couldn't get enough of me.........
Well, that's my experience in a nutshell; thing is, you know her better than anyone on this board ever will, and have to make your own determination. From what you have said, my advice would be to go get her, but only do it in small doses so you don't unknowingly ruin her fantasy.