Why do you want to go on T3 only?
With those results, you actually need to get TSH down to nearer one to see how well you convert T4 to T3 before making any decision about T3 only.
I think your endo needs educating, and here's a good start from thyroiduk.org.uk/tuk/about_... > Treatment Options
According to the BMA's booklet, "Understanding Thyroid Disorders", many people do not feel well unless their levels are at the bottom of the TSH range or below and at the top of the FT4 range or a little above.
The booklet is written by Dr Anthony Toft, past president of the British Thyroid Association and leading endocrinologist. It is published by the British Medical Association for patients. You can buy it in pharmacies or from Amazon for £4.95 and it might be worth highlighting the relevant section to show your GP and endo.
Dr Toft 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 email email@example.com for a copy of the article, print it and highlight question 6 to show your GP or endo.
Then ask for an increase in your Levo to achieve the results recommended by Dr Toft.
TPO Antibodies 450(34)
These high antibodies confirm autoimmune thyroid disease aka Hashimoto's which is where antibodies attack the thyroid and gradually destroy it. The antibody attacks cause fluctuations in symptoms and test results.
You can help reduce the antibodies by adopting a strict gluten free diet which has helped many members here. Gluten contains gliadin (a protein) which is thought to trigger autoimmune attacks so eliminating gluten can help reduce these attacks. You don't need to be gluten sensitive or have Coeliac disease for a gluten free diet to help.
Supplementing with selenium l-selenomethionine 200mcg daily can also help reduce the antibodies, as can keeping TSH suppressed.
Gluten/thyroid connection: chriskresser.com/the-gluten...
Are all your vitamins and minerals at optimal levels to allow thyroid hormone to work properly
Vit D - 100-150nmol/L
B12 - very top of range
Folate - at least half way through range
Ferritin - half way through range