If you don't respond to levodopa by noticing that your symptoms improve, that could mean that you don't have Parkinson's disease as I understand it.

Then there is your tremor, which is typically a resting tremor in PD but not for you. If you meet the other criteria, you might want to assume you have PD anyway until someone comes along with a more appropriate diagnosis.

Rereading the material in that link I posted earlier, I'm finding that some people "don't respond well" to the levodopa/carbidopa routine. There is another option, deep brain stimulation, but it involves surgery. I'm guessing you'd prefer not to go that route, or at least that would be my choice.

But they also mention "Other Therapies," and these might actually help you. Worth a try? You do seem to have other symptoms/signs of PD, and since there's no diagnostic test that would clinch the diagnosis, you might be well advised to take a conservative approach such as outlined below: