I can relate to the difficulty of marking how you are feeling. What I do in that case, is make a list of the symptoms I am feeling and knowing which symptoms belongs to what (manic/mixed/depressed/cycling) that helps. If you are cycling up and down, I just put one mark for depressed (whatever level that might be) and the another mark for hypomania/mania and draw a line between the two marks. I have also included an area that states how many mood changes I've had that day (and that is tricky, but I try my best).
Even an idea of how you are feeling works...and sometimes not knowing where you are indicates rapid cycling or a mixed state.
Glad to hear you're going to do some reading. Not only do you gain knowledge but I always find it comforting to read about my illness because it makes me feel like I not alone and that whoever wrote that book knows what I am going through. Anytime and in anyway I can get understanding I am comforted a great deal.