Is it therapy stuff interfering with your schoolwork, or is it mental health stuff, or treatment stuff? Therapy stuff can generally be resolved fairly quickly if you're both honest with each other - or you find another therapist. Mental health stuff is much more longlasting. Treatment stuff is a necessary evil.

How I differentiate:
Therapy stuff - transference, worrying about session, obsessing over T, stuff like that
Mental health stuff - your actual/initial issues, such as depression, anxiety, things like that
Treatment stuff - feeling tired after a session, still being out of sorts on Tuesday in class if you had T Monday afternoon and the session was heavy, touching on trauma or other deep stuff, or something.

Do you see the difference? Is it truly therapy stuff that's interfering or is it (also) one of the other two options I listed? (there may be even more options - I'm not an expert)