This story is very similar to mine. I was put on T4 but remained very ill. Did research and paid for private blood tests and discovered that despite TSH and ft4 being optimal, my ft3 was low.... I was not converting. Referred to an endocrinologist who told me there was no evidence T3 is beneficial to patients.
So had to go it alone with no support or monitoring. I bought online, started on a very very low dose and it changed my life. I had a life again. Have now self sourced T3 for years now. My GP is aware, it's on my medical records but there is no monitoring. My GP has admitted that I know more about the thyroid and my levels than he does.
I would love to have options (eg T3 or NDT) and proper medical monitoring by a medical professional but I'm stuck buying it myself, just to be well.