I have an oximeter at home. it seems to be functioning ok as my wife and daughter test with normal readings of oxygen levels and pulse. i only get 90 or 91 for oxygen levels. should i be concerned? pulse is mid 60s to 70?

That is a low resting reading. Are you a smoker? Do you have copd or other pulmonary diseas? . If you're short of breath and your reading is only 90, I recommend being examined in the emergency room and obtain an arterial blood gas determination which is very accurate. (Bring your oximeter with you). Other lung testing may be needed to look for pulmonary fibrosis& other lung pathology

You did not mention if you are African American or have a dark skin. May not work as well Get it checked out by a real oximeter at hospital. Esp if any COVID symptoms. Do it now.