Actually, four months stable does not equal infrequent episodes. If a person has more than four episodes a year, it make him a rapid cycler, which is not as common as a non-rapid cycling, as far as I know.

Plus, diagnosis of bipolar is for life. If you had at least one full blown manic episode, you will technically always be bipolar.

Now, saying all that, it doesn't mean that bipolar person can not stabilize for a very long time. Even without medication. I was taken off my lithium two month ago, but only after I was stable on the very low dose for three years. Before two years my pdoc would probably hospitalize me on the spot if I even mentioned getting off my meds. He is looking at me as a ticking bomb now still lol.

If I were you, I would have enjoyed my stability, made peace with the fact that I was not a plain boring neurotypical person and did not look for trouble when I didn't need to. If you continue to be stable for several years getting off your lithium will become very clear possibility. But that is after years, not months of stability.