I need advice

I was diagnosed with Hashimoto’s disease when I was 10yrs old, I’m now 23 and have been on levothyroxine ever since, my current blood tests show a TSH level of 20.90 and my doctor upped my dose to 300mg (the max) I feel like this is a never ending battle to try get my levels right and it’s just not working at all! I don’t know what to do, I’m so tired all the time and I feel like the symptoms have been gradually getting worse, what should I ask my doctor, what are even the next steps in this?