Teaching/Pumping

I’m a teacher and pumping during my breaks at work + after school.

Because of this, I have to pump right after my last class or I will literally explode since I teach back to back for 3 hours straight.

After school we have tutoring, but I cannot make myself available until 20min after the last bell because I go to pump.

How can I explain to parents and students that I am pumping... without saying that I’m pumping... but will be in my room eventually for tutoring.

I’m stumped lol!