The way I see this unfolding is,
Nora woke up early, ventured outside, went down to the river near the accommodation (where she may have been spotted bathing by a passer-by). She didn't have a concept of how vast and confusing the jungle is, and as she was enjoying herself in the water she began to follow the river until she realised she didn't know where she had originally entered, so she couldn't find her way back and quickly became lost and confused.
She panicked and zig zagged around the jungle, but with the river likely the only distinct geographical landmark amongst the vegetation she naturally ended up following it, but in the direction away from her accommodation, up until the point where her body was found.
Had she sat still at the point she realised she was lost, she probably would have been found alive.
I find it a coincidence she was found near the waterfall (it was claimed she had been excited to see) because I don't think she could have navigated there. The waterfall is part of the natural course of the river, which I think she entered near the accommodation and followed to the waterfall. The reason she died near the waterfall is because she was exhausted and because the terrain becomes more dangerous here.
She probably didn't sleep properly for days. When people were searching for her she may have been asleep on the forest floor after several sleepless nights.
As for the reason she was found without clothing, it may have been because she removed it after becoming too hot, damp and uncomfortable after being wet from the river.
Why Nora out of character left the house that morning we will probably never know. I don't think someone else is involved anymore, I think its a series of unfortunate events.
I was really hoping they would have found her alive
