Welcome to our forum and I am sorry you have hypothyroidism.
Few doctors know best how to treat patients as they seemed to have learned that just taking the TSH into account is all they should take notice of.
We have to read, learn and ask questions. I will say that to be on a 50mcg starting dose since Christmas is dreadful and you should have had a 25mcg increase every six weeks until you felt well, with a TSH of 1 or lower.
Unfortunately, again, doctors believe once TSH is somewhere in the range their job is done. No it isn't. The aim should be to relieve all clinical symptoms and make patient well.
NDT is the very original thyroid hormone replacement, since 1892 up until the 60's when the introduction of the blood tests and levothyroxine began to replace NDT. Doctors used to prescribe it but I assume with big pharma's promotion of it and especially in the USA with monetary rewards, NDT has fallen out of favour and will rarely be prescribed in the UK.
You may be well on levothyroxine and millions do fine on it, but there is a section who cannot as it is synthetic T4 only and has to convert to T3. T3 is the only active thyroid hormone required in the billions of receptor cells. You can look upon T3 as the battery of the thyroid hormones.
You need higher doses of levothyroxine and the new doctor will do so. Levothyroxine converts to T3 but you must have a high enough dose (gradually increased).
If you've had a recent blood test get a print-out each time you have a blood test for your own records and you can post if you have a query. for responses from members.
The usual doses members used to get were between 200 and 400mcg NDT. but the organisations have reduced doses down, sometimes too far and ignoring symptoms.
When you have blood tests for thyroid hormones it has to be at the earliest possible time, fasting (you can drink water) and allow a gap of 24 hours between last dose and test and take it afterwards. This allows the TSH to be at its highest as that seems to be the only number doctors notice.
Always get a print-out of your results for your own records. To recover it is a slowish process as we have to increase hormones gradually.