Do you find yourself grinding to gain levels? I ask because I probably would've around mid-way through if I were on harder difficulties. I'm not sure how far you are, but the first real Deathbringer fight (not the one against the immobilized one but the one in that open arena I whined about a little) was a point where I thought there was a noticeable difficulty spike (in my case measured as "how many arrows do I need for this?") and if I hadn't been pretty capable I would've certainly stopped and done a lot of extra side-missions and random hunts to get Aloy a few more levels and HP.