You should definitely communicate with your psychiatrist or therapist to get more information.

That’s kind of silly. Yes, diagnoses can change, but saying that you’re suddenly “not bipolar” is a little weird to me. It doesn’t just go away. You can be baseline when you have bipolar. I think that’s an important thing to mention to your psychiatrist.

Sometimes therapists/doctors focus too heavily on the official, billable diagnose as outline by the DSM 5, the current diagnostic manual, instead of giving an explanation of the diagnosis that's meaningful for the patient. I'm only guessing, but it might be that your doctor meant that you don't seem to meet the list of symptoms for a typical bipolar diagnosis, some of which have to be observed overtime, but still have symptoms of a less well defined mood disorder. It matters to professionals for insurance purposes but isn't as helpful for patients unless their doctors explain the change in diagnosis. My diagnosis bounced around a lot for several years too. Making it sound like you could just stop being bipolar was just a poor choice of words on their part. Perhaps they were questioning the initial diagnosis but they may have just been rushing to check off the right boxes and get through their paperwork effeciently. Find a doctor who will include you in the discussion of what your diagnosis is, why, and what information that gives you about treatment. If your mood swings effect your quality of life and ability to function, then it warrants working with a doctor. Ask questions! If they don't give you straight answers or an answer you can wrap your head around, call them out, insist they explain again. It's your illness, you should always be part of the plan.