The same sort of thing happened to me in my freshman year. I had been diagnosed with depression at age 8. I'd not seen a therapist for yrs but started again, & the 2nd term took 3 fewer hrs. My T helped me realize that as stress went up I'd need more rest, more energy to complete tasks. He was right.
Now I know I was actually bipolar, not just depressed. But in any case I had to incorporate my handicap into my schedule. I expected just as much from myself (& got it) but just not at as quick a pace as when I was living at home & in high school & life was just generally easier.
I also had to learn to keep my focus on specific tasks. If I looked at all I had to do In a semester, for example, I'd get overwhelmed.
Hope this helps. Enjoy college!