When I had issues with school, work, and studying I devised a plan to organize my time efficiently, and created a daily schedule for myself. I would always try to squeeze in my workout even if it was just for 30 min. If it was a really busy day I would sleep 30 min-1hr later just to rack in a bit of a work out, or wake up earlier to workout.
Obviously school is important. What you do right now school-wise (even the smallest thing, trust me) effects you later in life - whether it be in a good or bad way. I'm not saying to stop working out, but don't be afraid to put it on a back burner at the moment.
If you still wanna squeeze in a workout, pick some of the 10-20 minute ones here on the app.You'll still be working out, but not spending too much time. I'm an organization freak so everything I do is planned. I just got done with finals myself. Which means I had to rearrange my own schedule - I had to adjust my workouts around my study time, cooking, chores, as well as the individual classe's final exam schedule. It's doable.