Could i have asthma with normal oxygen levels and normal chest xray?

Yes: Yes it is possible; since the (smooth muscle) constriction of the bronchi can not be seen in chest x ray. Most people with asthma have normal oxygen levels most of the time (even during attacks, respiratory rate, heart rate will tend to compensate the hypoxia).

Yes: A chest xray will not detect small airway narrowing and wall thickening.

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.