Hi Lyle I'm 19 years old and I also suffer from very similar problems. I've never been diagnosed but its obvious I have bipolar 2, I've had cycles of both hypomania and depression.
I never really realised until recently that my actions were in a pattern like this but I'd say I'm on the pretty extreme end of it. My teenage years have just been crazy looking back. Highs of extreme energy and then the lows set in.
I can definitely relate to not wanting to seek help when you're depressed I always get the feeling of what's the point and not to mention I'd feel embarrassed talking to people about it.
My sleep is especially bad during my depression stages something I see you struggled with as well I just cannot fall asleep even though I am exhausted.