My breathing seems shallow and it's harder to breathe sometimes. real or imagined?

Can be asthma, etc.: It depends on the circumstances and setting in which these attacks occur. They might be panic attacks, where part of the therapy is to breathe into a paper bag to slow brreathing down and relax. It can be an asthma attack triggered by a thing like cold air. It might be a heart attack. It would help to see your doctor to pinpoint the cause.