hey there
sounds like bipolar to me. You just happen to be in the category that has long periods of wellness in between episodes.
literature reports to us that many people come out of episodes on their own without the help of meds. Everyone is different.

I would monitor your moods when you start to notice warning signs. Perhaps have an as needed med to bring you down when you are headed manic. Keep stress low and make sure you sleep.

Welcome to PC!