I sympathise. I'm freezing too. In my case, it's because the tumble dryer vents out of the window in my bedroom, which is my own fault, but being cold is rubbish for whatever reason.
I have found that wearing overtrousers helps. They are made for hiking, but wear them over my normal trousers.
I find that having tights or thermal trousers under leggings can make me colder for some reason. I get on better with looser trousers with looser overtrousers on top.
I wear a thermal long sleever roll neck top with a roll neck jumper on top. I then wear jersey leggings with over trousers and sometimes knee length boots. I find that a breathable waterproof coat really helps too.
Are you in the west of the country by any chance. When I lived in the west I found that the cold went right through me, because it was very humid cold. I'm now in the east and the air is dry and I don't get nearly so cold. Here the cold just stings my skin rather than going through to my bones as it did before.
Being very thin made me cold when I had long covid and also something called hypovolaemia, which meant I didn't have enough fluid in my body, but that is a more extreme thing. In that case I couldn't get my body temperature above 35.8C. I had to go to the hospital for that. You would know if your body temperature was that low.