Hi Kathleen & Penelope,
It did occur to me that I may have been dealing with low Thyroid function for some time without realising it. As I've said before I asked for a Thyroid blood test 18 months ago but wasn't treated as I was just within the normal range. Given that hormones fluctuate throughout the day I assume my thyroxine levels could've been much lower at times.
I think we're all probably right in suspecting any earlier classic symptoms suggest our later diagnosed thyroid condition predates that diagnosis & possibly by a considerable time.
I feel for you both because as mentioned before, by the time my Hashimoto's was diagnosed in my early 30s, when I already had a goitre, I'd had some of the tell-tale symptoms for a good few years, though in the early stages not to a debilitating degree. I was lucky the goitre (small but contained a suspicious nodule) was noticed by a surgeon treating another condition. He did a biopsy there & then which showed sky-high antibodies, arranged a hemithyroidectomy & prescribed a low dose of thyroxine to prevent further enlargement of the goitre during the 5+ months wait for surgery - all before I left his consulting room that day. Very kind of him, as he was not an Endocrinologist & in fact it was some years later before I even got to see one.
Suspecting hypothyroidism was behind my health probs, which had become so debilitating I'd recently left my job, I'd repeatedly asked my GP whether I might have a thyroid problem & was always told no. I was never told hormone levels from any TFT carried out before the biopsy confirmed Hashimoto's, so I don't know whether they were within range or possibly mildly abnormal, i.e. at a level where it's not considered sensible to start treatment. There was less transparency & a more paternalistic attitude than there is these days.
As soon as I was diagnosed I made sure always to find out & make note of my TFT results, though there was often resistance to my having them - the standard response being "the doctor is happy with them". As receptionists were never authorised to let patients have their results, I felt bad about having to be put through to a busy GP for these. The doc would then usually just say "they're fine", so I'd have to push uncomfortably for detail, with one GP I remember asking crossly why I wanted to know. Not an issue now, as needing T3 means I have to see a private Endocrinologist & have bloods done privately.
Pretty much as I sense you both are with your situations, I was shocked by the diagnosis of Hashimoto's with a goitre requiring surgery, which seemed to explain a lot. Started to learn all I could about thyroid conditions, both for self-help & to be confident I could hold my own with medics & have some control over treatment. I always recommend that newly diagnosed patients do the same, as it's unfortunately a field that seems to be poorly understood by many medics & many patients don't ever get to see an Endocrinologist, "uncomplicated" hypothyroidism being considered appropriate for GPs to manage.
Also very unfortunately for patients, as with menopause, there's controversy over treatment & we often face a struggle. As Penelope has sadly found & as mentioned earlier, there's debate about the point at which treatment should be started. The need for T3 is another serious, polarising issue for some patients, as is the use of "natural" thyroid extracts such as Armour, which some feel better on than synthetic replacement hormones.
The Thyroid UK article by Dr John Lowe I suggested earlier Penelope might like to read is interesting as it deals with the issue of whether or not raised antibody levels give rise to symptoms in patients whose hormone levels are within the ref range. My feeling is that if there's a disease process ongoing, as there clearly is, there will likely be systemic effects from it. I'd long understood that patients with Hashimoto's can experience symptoms of both under- & overactivity as the condition progresses, the antibody attack causing the thyroid to release hormones in a haphazard manner. So that over time there can be hormonal chaos, comparable to what happens in perimenopause as the ovaries progressively fail. So I'll be very interested to hear what your Endo has to say in response to your question on this subject, Penelope & I do hope you manage to get appropriate treatment if your HRT leaves you with symptoms that are clearly thyroid-related.
Kathleen, though I knew that thyroid hormone levels fluctuate throughout the day as you say, I was surprised to learn only a few days ago as mentioned above to Baby, that being tested after eating has been shown to produce a lower TSH than if bloods are taken in a fasting state. This obviously has implications for both diagnosis & management.
It's a huge field & beyond the basics, hellishly complicated to get to grips with, so we're all up against it to some extent. Can only help to share experience & any knowledge or insights we manage to gain. Please keep posting everyone, to let us know how you all are. My heart goes out to you.

Wx