I found that a varying schedule made it difficult for me to get anything done in college, which is tough because class schedules definitely change from semester to semester.
I used to wake up at 6am and hit the gym first thing. It sucked getting up early but you get used to it and will have to do it for the rest of your life soon anyways.
I did plan my routine around party nights though, no way I'd get up with a hangover and of course weekend training was ideal, you don't really have a schedule.
As far as classes, I had two three subject notebooks as I usually stacked classes 3 per day mwf and t-th.
I would study each previous classes notes while I waited for the new one and intentionally staggered them half an hour or so. This usually meant when test time came I could pretty much just review notes and be fine, outside of memorizing statistical formulas or economic charts and shit.
I really don't see what is so tough about your schedule though. You have your time blocked out pretty well. Just use a little discipline and stop stressing.