For me, it's easier to remember the depressive episodes just because they are more obvious and you definitely seek treatment for them. Whereas the hypomanic episodes don't really stick out that much because maybe you were just having a great time how ever many years ago, and you are not really able to pinpoint that exact moment in time.
I understand thinking that the medication may not be doing it's job and it is possible that you just happened to feel better, but what were your previous depressive episodes like?
It is also hard to accept a bipolar diagnosis for many people. Who wants to question their behavior that way and have bipolar attached to it?! At the end of the day, after all your researching and comparisons between your behavior and what you learn start to make sense, the medications are working, and therapy is going well, it's easier to "settle" into the diagnosis and be vigilant about not having it take over your life. Please take care: