You are very under medicated. The aim of Levothyroxine is to take high enough dose to bring TSH down to around one and FT4 near top of range and FT3 at least half way in range.
Your FT4 is actually below range
Make an appointment and ask for 25mcg dose increase, with bloods retested after 6-8 weeks. Likely to need further increases, always in 25mcg steps and retesting each time
Very likely to also have low vitamin levels. Have you had recent tests for vitamin D, Folate, ferritin and B12?
If you have these results and ranges add them to your post. If not been done ask GP to test.
Have you had your thyroid antibodies tested? High antibodies means you have Hashimoto's also called autoimmune thyroid disease
All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH and most consistent results
Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine,
"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.
In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l.
Most patients will feel well in that circumstance. But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.
This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."
You can obtain a copy of the article by emailing email@example.com print it and highlight question 6 to show your doctor.