Hi, are you veterinarian? Or, sorry should `t ask if you got any conditions. Do you carry a tent or any sort that will black you from wind since wild chill is big matter. My suggestions are try eat lamb or goat meats often before you go. -11 sleeping bag depends on quality, maybe buy another one because you said your bag weights 1.9kg but only 300gm, my warmest is -28c, 450gm almost same weight like yours.
Our body is like an engine, should keep it running and running it will need fuel, I burn body fats even when I was asleep, some people will need jogging. So, keep feeding yourself with protein, carry some beer jerky.
Beef jerky, why all the jerky are sweetie in here? Not salty with bit of greasy...