Can I marry a girl when according to her DOB she is not a major

I want to marry a girl,whose dob is 7 nov 1998 on certificates and he is not 18 by this dob but his actual dob is 17 april 1997 but there is no documents to prove this dob as she is not having birth certifiacte.she is ready to commit orally that she is ready to marry by her will and she is voluntarilly fleeing away wid me,she is ready to sign on documents.we cant wait till nov when she will be 18,plzz suggest me is there any legal way to get married in a way that her family cant put criminal cases on me and she cant be seperated from me .she is in same caste and not minor