Seeking help to know about the Rights of an Employee

Good evening I have been working for one of the reputed schools of Delhi, India. It’s a private School located in the prime location of west Delhi. I was appointed as Hindi Teacher (PRT) on 15th October, 2015 on consolidation salary with an appointment letter mentioning expiry date till May, 2016. I continued to work with same salary after that. I got married in February. 2018 and gave birth to my daughter in 03rd March, 2019 and the last day of my in School was on 1st March, 2019. During my pregnancy period, I didn’t receive maternity leave and I worked for entire nine months of my pregnancy. The new session in schools in Delhi begins from April every year. I called in School during last week of March, 2019 to ask School authority when can I join, and then the HR of the School gave me the shock of my life that I am no more part of school and school has discontinued my services. Since then I have been fighting.