Sorry, I missed this question. Yes, 8 week cycles are the best because like I said, or the article says is that Myostatin will stall a cycle at week 8. We have known this for years, that's why myself and my circle of friends stay on all year.
Now, I don't know what your objectives are, so I will speculate that you just cycle. There are some things we can do to extend a cycle past week 8 but it will only be extended maybe three weeks for more LBM gains.
First, you could add a more anabolic compound at week 8, but you being a female and already take NPP I'm not quite sure what you would be able to add that's more anabolic that would not give you adverse effects.
We also add an oral around week 7, which will give another 2-3 week extension but that would be it, that cycle is history after that.
Also, believe it or not, creatine is known to combat myostatin to a degree. Therefore, my suggestion to you would be add anavar with creatine at week 7, that should give you another 2-3 weeks of LBM gains. Moreover, anavar and creatine have a good synergistic effect together, so this might be your ticket.