Maybe invest in some cheap thermal underclothing-- a long sleeve thermal top, and cuffed leggings so you're not getting a draught going up your legs. It's better to wear several thin layers, so you could add a lightweight gilet between the hoodie and jacket. You could also add a thin scarf to keep your neck warm if you can't wear a hat.

Thin thermal socks that you can wear comfortably in bed without making your feet sweat, and under your normal socks when you're working. Thermal half finger gloves might help keep your hands warm. You could try getting a small plug in ceramic heater that will warm up the immediate area around you without using much electricity.

It might be worth getting a blood test for your thyroid, as an underactive thyroid gland can cause temperature dysregulation.