The lab can only report what they find. But, if you are legally authorized to take the medication, that is good enough in most states, unless you have a job such as air Traffic controller in which they heavily regulate what medications you can take while on duty.
As the previous attorney states, if your doctor authorized you to take the medication, you should not lose your license. I would provide documentation to the Department of Licensing of everything you've described above, and appeal their decision to revoke your CDL. There may be administrative deadlines for any possible appeals, so be sure to respond in a timely manner. You may also wish to consult an attorney experienced in dealing with administrative law issues.