Recently it occured to me that she is more sativa dominant----maybe that's why she is on the later side and her genetics may be not as good as Dinafem.Let her go, She is starting to set them now, I can see them in pics! If ya really want force flowering, you can set her in dark for 18-24 hrs, that should surely get things moving...Possibly. I have same issue going on with my Auto Amnesia, I'm at day 46 today and still no pre-flowers, your much more advanced then mine is even..
Yes, letting her go...on her own seems to be best alternative to me too.