Rosehall To still be on 25mcg Levo two years after diagnosis is ridiculous. That is just a starter dose for children, elderly people and those with a heart problem.
What should happen after starting Levo is that thyroid tests should be repeated 6-8 weeks later, an increase of 25mcg, another retest follows after 6-8 weeks, another increase of 25mcg, etc, until symptoms abate.
What you need to do is ask your surgery for a print out of your results. Your GP won't tell you, you have to ask. And don't just get the results verbally, get a print out so there are no mistakes or misunderstanding. You are legally entitled to them under the Data Protection Act 1998 so if they are reluctant to give them to you just mention that it is your legal right to have them and that you will call back the next day to give them time to organise and print them. Make sure that the reference ranges are included.
If you haven't had a test in the last year then you are due for one so book it and also ask for Vit D, ferritin and folate if these weren't done when your B12 was tested. Also ask for thyroid antibodies to be tested.
Post all your results with ranges for members to comment.
Your B12 is more than slightly down if you are having injections, that means you are B12 deficient (it will be under range). Folate is usually done at the same time and if that is also low then you should be given folic acid. Whilst supplementing with B12 you should balance all the B vitamins by supplementing with a B Complex as well.
*Important* - When having thyroid tests always book the very first appointment of the morning, fast overnight (you can have water) and leave off Levo for 24 hours (take after the blood draw). This gives the highest possible TSH which is what is needed when looking for an increase in Levo or to avoid a reduction. Do this every time as continuity of conditions means that you can accurately compare your results every time.
The aim of a treated hypo patient generally is for TSH to be 1 or below or wherever it is needed for FT4 and FT3 to be in the upper part of their respective reference ranges.
Read and learn about your condition so that you can discuss your treatment with your GP confidently, otherwise you will be left undermedicated and will remain unwell. Check out ThyroidUK's main website, thyroiduk.org.uk/tuk/about_... and work your way down the menu on the left hand side.