If you are regular employee of the school and have proper documentation, then you will be covered under Maternity Act and also job security been taken care under this act. You need to give a written application to the management not for 3 months but for 26 weeks of maternity leave. After getting an reply from them in writing you may decide further course of action. Also, if they deny in writing then you can go to nearest labor office for assistance and seeking help from them. They will surely be helpful in this matter.
From India, Indore