Sick kids in school

Parents when do you let your kids stay home when they feel ill ??? Or what symptoms

My daughter just started school. She’s on her second week and I don’t want her missing just yet or when she is far more sick (strep throat,flu)

Right now she has a cold and cough no fever just congested and cough runny nose so I still make her go I gave her cough medicine in the morning send her with cough drops and a water bottle

My sisters kids are all sick same with a cold and she kept them all home so I thought maybe I’m mean by sending her! I usually only let her stay if she has a fever, diarrhea, vomiting which I usually take her to see her dr but a simple cold I can’t let her miss or make an appt for a simple cold. I am wrong or what I need other parents opinions please! She’s in second grade and another reason is I’m scheduled to have my baby next week and I’d rather her save days to miss when baby comes but even before being pregnant these are the rules I stand by

Opinions please!!!