I'm so sorry you're in this situation. I've been there too and remember the cold so vividly..
You've probably been given all the advice possible, but thought I'd add what I used to do when my boiler broke mid-winter and I couldn't afford to replace it..
I used to heat 1 room only, and that was the room we all huddled in.
Hot water bottles wrapped in a towel and wrapped on my body with a belt. Feels amazing.
Soups for dinner. All you need is water, stock, onion, root veg and some protein (sausage, frankfurters, bacon, chicken left overs etc) if I have no potatoes, I throw in some pasta or spaghetti.
Cinnamon and sugar on watery porridge. Splash of milk on top if you have it.
Woolly socks. Always
Bed sharing with DC. But they must bring their own blanket so that everyone stays warm.
Wearing a hat to bed. Yes really!
Hot hot baths, but only deep enough to cover your body if you lie flat on the bottom of the tub. Saves water but warms you up.
Hope things improve for you soon. It's so hard and you feel the cold in your bones. I'm sure you're doing amazingly though.