With all that you do, you must use a planner of some type to organize everything. I like to plan my week on Sunday evening and when I do that I also decide when and what kind of workouts I am going to do for the following week and I can get a feel for how hectic my days are going to be.
What you could do, either daily or weekly is look at your schedule and figure out when, what, and how long you can exercise. Don't plan a 2-hour workout if you are going to be out of the house until 10pm. It probably won't happen. But you might be able to fit in a 20-minute run or walk sometime in the day. The more you do this, the more you will realize what works and what doesn't. For me, planning to do things in the evening don't work unless I plan them with someone else because I easily talk myself out of it.
Good luck. Have a good school year and be sure to get enough sleep.