Is it possible to still have asthma with normal oxygen levels and normal chest xray?

Yes: If you are not having a flare of your asthma. If flaring, your oxygen level may lower as the flare worsens and your chest x-ray will likely show (if done) hyperexpansion of the lung fields due to air trapping.

Yes: Between episodes an asthma patient will usually have normal blood oxygen levels and chest x-rays. Someone with recurrent episodes over a period of years may have suggestive changes on an x-ray, but the findings are not specific to asthma.