Pregnancy-related dismissal, what should I do?

Hello. I am a foreigner currently working as a freelance English instructor in South Korea. Recently, I received a notice of termination from one of the companies I work for, citing my pregnancy as the reason. I would like to hear your opinions on this situation. The company I work for manages my schedule and assigns me to schools and classes. There is also a contract in place regarding this. The problem began when I informed them of my pregnancy. By mutual agreement with the company, I decided to continue working until August, and during my first trimester, the company said they would assign afternoon classes to another instructor, but in the end, I had to handle all the classes. Recently, I was informed that starting in June, I would be replaced by another instructor because my pregnancy has entered a stable phase. I find it unreasonable that the reason for my termination is concern over my pregnancy. I've also heard that as a freelancer, I cannot be protected by labor laws, which has left me confused. Can I seek help from the labor office or relevant organizations? I need your experiences or advice. Thank you.