You know I have BP disorder. If you want to "talk" about it, email me. I think you need to discuss this in detail with your new doctor and let him/her decide if they think that's what it is. I would never accept that diagnosis from a general practitioner. It needs to come from a psychiatrist who is trained in this area.
I was in denial. I kept going from one doctor to another, hoping to get one to disagree with the others. After the 5th psychiatrist said, "You have bipolar," I decided to accept it. Actually, my husband said, "How many doctors are you going to go to before you believe them?" (I'm a little stubborn!)
And no, the highs and lows do not have to be extreme---and they do not have to last for days or weeks at a time. You can cycle from one to another rapidly (within a day)---and have both mania and depression at the same time. There are all sorts of classifications of BP. Some are worst than others.
The good news is you can get treatment for it--and you don't have to suffer with it.