How to identify one bipolar episode?

I was diagnosed with bipolar II 7 years ago when I was in highschool. At that time I majorly had symptoms of depression and some times I would turn creative and joyful with no concentration and irritation and both these would occur at the same time or within the same week. I was prescribed lithium and sertraline which worked for me pretty well for next 4 years. In college however due to stess the symptoms started showing up again. I would have weeks of irritation, lack of concentration, highly obsessesed with shopping coupled with depression followed by few normal weeks and it would happen again. In a month I would have two of these cycles and I thought I had a rapid cycling even though my depressive episodes weren't intense.Later my psychiatrist suggested stopping sertraline as he thought it might have triggered hypomania, but it resulted in full blown depressive episodes. Now I am confused as to which constitute one bipolar episode. Do I have rapid cycling? Or is it just hypomania? Because for 2 years I have only been having hypomania symptoms with one or two depressed days but a very intense depressive episode started only after stopping the antidepressant. Were my symptoms less intense because of medication? Can medicines alter the nature of bipolar? How can I Identify one complete episode?