I would tell you in India the boy needs to be 21 to be eligible for marriage.
Now coming to your query, It is illegal to be forced to get married as per Article 16 and Article 23. Such marriages are Voidable.
Immediate steps to be taken:
1. You must contact Women protection and welfare cell in your local police station and file for domestic violence and cruelty against people who are forcing you to marry.
2. Contact National Commission for Women and file your complaint against such act.
3. You can file a criminal suit but make a mutual decision before you proceed.