I applaud your efforts in seeking to know more about Bipolar Disorder. Please don't think of yourself as being dense, in fact i would say that most people haven't a clue.
In my view that even includes the psychiatrists and mental health professionals too. I certainly don't understand it, but i wrestle with what are two very different cycles, at least that's how it it is for me.
I was diagnosed with major dep episodes of extreme depression about the age of 18 while I was in the military, after a suicide attempt. Throughout my life i have been plagued with periodic I only sought out help when in those extreme lows when i wanted to give up and end my life all over again.
I was diagnosed with Bipolar Disorder last year, at the age of 53. Like you, i didn't want to believe it either. I started attending Group Therapy, which has given me tools that i use to keep my life in some semblance of order.
I also gained a thirst for knowledge about learning more about Bipolar Disorder. I figured that if i have to live with it, then i may as well learn all that i can about it.
It kinda gave me a laugh when you said that my hypomanic phase sounded normal to you. I've heard it often. Just like I've heard comments about depression like "everybody gets depressed sometimes", sound familiar?
Has your therapist mentioned bipolar again? Ask her straight out what her diagnosis is.
To learn more more about Bipolar Disorder type it into Google. Also if you type in DSM IV + bipolar, you will get the "official" guidelines are for a bipolar diagnosis, same with DSM IV + hypomania.
My mood: very awake