You can be depressed and only have the difficulty learning, low desire, slow reactions, etc. Symptoms aren't always 100% the same each time, which is one of the things that makes it hard to identify and catch your episodes early enough at times. You mention hypomanic spikes, which could indicate perhaps you have some sort of mixed state?
You ask a great question. I believe without a doubt if someone is on the kinds of meds we are on it effects everything. We feel slower, not up to par, memory problems, forgetfulness, foggy, just not clear headed, desire to do much if anything and all the others you listed. The meds effect everyone differently and although some people may not have these problems, others do. Especially if one is over medicated or on so many drugs it really has an impact. The key to our own mind is to figure out the least amount of drugs we need to help us instead of letting the pdoc through the whole med cabinet every time you see them. We must be our own advocate and do our research. I am finally on one drug, it has been about 2 months and so far so good. I realize there are people who do need more but research and asking your pdoc questions is key. More is not necessarily better. Changing however can be.
And yes, as ThatQuietGirl stated, depression and or anxiety can certainly alter our thought process.