The intensity of my sleep apnea varies from night to night, and you might be similar?
Based on oxygen levels, mine also varies from subclinial to "medium" apnea. I was deemed not to have sleep apnea based on the take-home test or the in-hospital test... but I wore my oxygen-logging ring during the in-hospital test to check it was calibrated to the hospital's equipment (it was), and the specialist then diagnosed me based on my measurements of oxygen levels on other nights.
Based on oxygen levels, mine also varies from subclinial to "medium" apnea. I was deemed not to have sleep apnea based on the take-home test or the in-hospital test... but I wore my oxygen-logging ring during the in-hospital test to check it was calibrated to the hospital's equipment (it was), and the specialist then diagnosed me based on my measurements of oxygen levels on other nights.