Has your LO had a recent developmental spurt where she is more physically active than ever before? Just asking because I have read a few times that our older babies and toddlers *can* genuinely become thirsty in the night from lots of day time activity. In these cases, I have read to leave a sippy of water for the LO to help themselves to. However, I would think that your 9 month old might be a little young to figure out how to help herself to a sippy in the dark in the night and you may, of course, not be comfortable with this idea anyway.
In saying that, it sounds to me like she might just figuring some things out in her mind during these 'strange' NWs, you know, processing stuff from the daytime etc. Or..... and this is a contradiction to normal 'crib parties', but my LO had a long spate of 2.5 hour crib parties every single night due to OT, rather than UT (it was *very* confusing, because she only got upset at the end of the long NW when she became really OT). Kind of hard to tell. Hope you get some other ideas and advice that might be more helpful than my ramblings. LOL!!
Oh, just want to say, well done for changing up your routine to cut down most of the NWs - that is not easy to do - big pat on you and your LO's backs!!