Welcome to our forum
I assume when you say you are taking 2 x 25mcg that it is liothyronine (T3) and not levothyroxine.
There was a doctor, now deceased and I shall give you a couple of his links which will be informative. He ran the Fibromyalgia Research Foundation, Thyroidscience.com and Drlowe.com. These have now been archived but thankfully there is still info we can read.
You now have to, like most of us on this forum, read and learn more and take yur own health into your own hands (as much as possible.
On the following link you will see that Fibro patients are usually thyroid hormone resistant, which means they need more T3 than other patients.
Lots of info on the one below (see topics at top of page). On any of these links I've given, some links within the topics might not be accessed due to being archived.
I am assuming your 25mcg x 2 is not levothyroxine as 50mcg would be an extremely small dose. In the UK they have been told to only diagnose patients when TSH is 10 (some doctors luckily do take symptoms into consideration and may prescribe when lower than 10).
When you go for blood tests for thyroid hormones or fibro get the earliest possible appointment and don't eat before it although you can drink water.
Allow 24 hours between test and last dose of thyroid hormones and take them afterwards. This allows the TSH to be at its highest as it reduces throughout the day and taking food also lowers the TSH. The aim for you should be a TSH of around 1 or lower.
Also ask for Vitamin B12, Vit D, iron, ferritin and folate to be tested and thyroid antibodies too.
Always get a print-out of your results (we are entitled to by law) and say you want it for your own records) some surgeries charge a nominal sum for paper/ink.
If you have a query you can post but the ranges have to be stated because labs throughout the UK use different machines thus different ranges.
(I am not medically qualified and have hypothyroidism but take T3 only).