Was I too harsh?

I am an instructor and I teach pediatrics for nursing majors. There is this student I have that is late every single day without fail. I pulled her aside after class and asked her about it and she told me she's sorry. She has ADHD and her medication has been on back order. I told her I get it. My son has ADHD. But when she's a nurse and working in a hospital this won't fly. She will have patients who need her. Class starts at 9:30. If she needs to tell herself class starts at 9 to be here than do that but she has got to figure out how to cope and make sure she's in class on time. She said ok and seemed a little emotional. Was I too harsh? I really do try to be understanding. I know life happens. But being late every single day isn't gonna fly in the nursing field.