Hello,
I think your weight loss should stabilize once your blood sugars do(you may in fact regain some weight).
Given your absence of family history, one important set of tests that needs to be done soon should include antibodies against islet cells or GAD(anti-GAD and anti-islet cell antibodies), as well as a serum C-peptide level. The antibodies are markers for Type 1 diabetes, and the c-peptide level tells you how much insulin your body is making on its own. If you had autoimmune thyroid disease, then you are at a higher risk for Type 1 Diabetes than otherwise.
That said, non-overweight people can develop diabetes, although they often do have family history as well.
In regard to the thyroid problem, it should have been diagnosed based on thyroid blood tests, so it should have been relatively straightforward to diagnose. Keep an eye on those tests too as you go along.
Hope this answers your questions,take care and speak to your doctor soon.
Thank you for your reply,
I have arranged for blood works now and an appointment with the doctor, so will try and get some answers from these.
Thank you for your advice.