No, MG cannot mimic COPD on an X-ray. COPD involves inflammation, MG does not.
COPD - Chronic Obstructive Pulmonary Disease
Until you can find a pulmonologist who will reevaluate your situation, you will not have an answer to any COPD questions.
You have a legal right to your records. If they don't know where they are, they are either lying or are open to a huge lawsuit due to incompetence. Put a request in writing to the medical records department. Then wait. There's no need for name calling or being upset. Just ask for them.
I personally have found that being kind to people, even if they are not good at their jobs or not being nice, can provide better results.
All doctors can't truly be incompetent, given the boards they have to pass. There have to be some doctors who can help you.
I hope you find someone to help you.
Annie