Re: waste of water...I reuse my hot water bottle water. When it's cold, I leave it in the bottle, then re-pour it in the kettle. No waste of water.
(That gets rid of half the argument of "waste")
Ok, so from what I'm hearing from you,
You've lost 7.5 stone (you'll DEFINITELY feel the cold more), you're in a desk job (sedentary) and you live at home with dad who is VERY tight with the heat/electricity usage ( boiling a kettle for hot water= wasteful, heated throw = wasteful etc).
Assuming your blood work shows no deficiency, no wonder you're so bloody cold!
I'd be freezing too!
Ok, so this isn't what I originally thought. I thought "you're an office worker, have to dress professionally and can't move much at work and you're chilly".
This is much more than that.
This is a pervasive all over chilled you can't escape from.
Since Dad won't turn up the heat and won't allow wasteful heated devices, you're gonna have to change your clothing. Invest in thermal underwear (they're modern and stylish...often a matching set and could be mistaken for regular clothing. They aren't "bra and panties" of course, but a full ankle to wrist set of top and bottom. Thin too, so they fit under clothes without bulk.
At home, can I suggest an "ear flap hat". Like elmer fudd on Looney tunes. LOVE mine. Keeps the heat in like you wouldn't believe. I slept with it on if I have to wash my hair in the evening and go to bed with a damp head.