Hi Flo2020
If your last thyroid function test was in Jan I think it's reasonable to contact your GP & ask whether it could now be repeated, describing, as you have for us, what measures you have to go to to get warm & how extreme your fatigue is. Also, as CLKD suggests, ask your GP whether a full blood count would be sensible, to see whether you could be anaemic. You should not have to pay privately for those, but I understand you may prefer to if you have the means - I also go private for issues the NHS can't manage for me.
Your coldness sounds extreme & coupled with the crashing fatigue, is suggestive of hypothyroidism, which can develop slowly, so it's possible that even though your last TFT was in range, the situation has changed since then. It's helpful to know the actual thyroid blood results, with the ref ranges as they vary from lab to lab, so if you can, try to get these from your surgery. It may be that your levels were already towards bottom of ref range.
Another thought is are you eating enough nourishing foods to provide adequate calories to keep you warm & give you energy?
Crashing fatigue can also be a feature of menopause I'm afraid & like you I often find from mid-afternoon I'm exhausted, despite well managed hypothyroidism & HRT. So it may help to adapt your lifestyle if you can, to ensure you get adequate sleep & whatever forms of R&R suit you best.
Sorry - was posting while you & CLKD were!