Sorry you're feeling so exhausted chipping - when I feel like that (like my legs weigh a ton and have to be heaved up the stairs) I'm fairly sure it;s been my electrolytes out of whack. I make myself a mug of beef oxo and drink it and have a piece of cheese and feel a lot better within half an hour. I see you're veggie, but maybe try a mug of veg stock and some cheese? Avocado and spinach also supposed to be good for sorting out your salts.
I might get Briffa and read it myself and pass it on, I've been meaning to!
Protein/fat wise. I'm sure you've tried all these, but veggie ideas of mine are:
Cheese of any sort (tomato & mozzarella, feta and olives, cheddar and gherkins, cheddar and cucumber/celery all nice combos, halloumi, paneer)
Cream cheese pancakes (but they include egg - are you no egg, or just no eggs as eggs IYSWIM? Can you cook with them?)
Greek yog with some seeds/nuts on top (I like sunflower, linseed and raw almonds)
Nuts (macadamias, almonds and pistachios are the lower in carbs)
Seeds
Guacamole with veg dippers
Avocado and cheese
Coffee & cream
Cream generally! Have you tried all the turnip/swede/celeriac gratins with cream? Lots of fat there.
Try Choos tartiflette off the recipe page if you want fat. Plenty of butter, cream and brie in that, and it is amazing.
Butter/olive oil/mayo (but eggs in that!) on veg/salad. If you haven't yet then do try halving a radish, butter it, dip in salt and eat. Very yum.
For a bit of a twist, go for garlic butter on your veg instead of straight butter.
There was a sag paneer recipe posted by someone a while back if you like curry? Paneer would be a protein source ? Sag paneer:
Toast some 1 tsp cumin seeds in a dry pan then remove and crush. Fry off some chopped shallots in oil add a chopped clove of garlic, teaspoon of ground coriander, the cumin, teaspoon garam masala and as much fresh chili as you like. Contiue browning until the onion is nice and soft. Chop your paneer into small pieces approx 1-2 cm cubes and add to the onion mixture, Continue over a low heat until paneer in slightly browned (1-2minutes). At this point I tend to just add my frozen spinach and leave it over a low heat to defrost and cook through. You could defrost separately and add after if you want. I use the chopped frozen spinach. You could add some cream at the end if you want a creamier texture.
Coconut milk - black has a recipe for spicy greens in cocunut milk from River Cottage Veg Everyday if that appeals?
Cauliflower and broccoli cheese?
No idea if any of that is any use but I hope so!
Thanks Bessie, that sounds not dissimilar to what I am sort of doing with the stew, except we'll have all the veg, chicken and stock all together I think for comforting warm loveliness. The carcass is in the slow cooker doing it's thing now, and I will leave it there overnight. It smells amazing! (As far as I can smell with this farking cold... )
The roast was SUBLIME. Oh how delicious. I have eaten so much chicken skin 
Like a helpless hoover pig.