If you have a minimum age of 17 years or you will turn 17 atleast by December 31st, 2019 you have fulfilled one criteria. Now the other important criteria is that you should have studied Physics, Chemistry, Biology/Biotechnology and English as core subjects. You should have atleast scored 50%. If you have fulfilled this criteria, though you studied Mathematics, because you have had Biology as well, you are eligible for attempting NEET. Hope this helps.