Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
I am sorry that you have been suffering for the past 8 years. The symptoms you describe can all be secondary to the underlying depression and anxiety. Anxiety, as you know, is a psychological and physiological condition with a multitude of symptoms. They include heart palpitations, muscle tension, fatigue, nausea, chest pain, shortness of breath, headaches, and GI symptoms such as diarrhea to name a few. Anxiety can also be accompanied with panic attacks such as a feeling of impending doom or death. Depression can cause something called psychomotor retardation. These symptoms include slowness of speech, decrease movement, and cognition difficulty.
Early onset parkinsonism can occur but is rare. A thorough neurological evaluation can differentiate parkinsonism from other etiologies.
I agree that if you are concerned about your symptoms, you should be evaluated.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
Sorry to hear your suffering. By the fact that you are worrying about parkinsons and the symptoms you stated I assume you think you have a physical problem instead of the depression & anxiety the Doctors diagnosed you with. I assume 8 years ago they did a lot of tests to try and eliminate a physical cause before diagnosing you with depression and anxiety. The best course of action for now is to see the neurologist and see what he thinks. After he examines you be direct and ask him if he thinks if your symptoms have a physical cause or is depression or anxiety the more likely candidate. I wish you luck, my friend. Post back and let us know what they find.