I think she turns 18 today. So if you marry tommorow age will not be the issue. But there are many other things which you should understand before taking a step.
Please be sure of your love, that if her parents take her home with her, she should stick to the stand and not agree with her parents, iif they file cases against you for forcing her to marry you, rape, kidnapping, extortion. I do not wish to discourage you but this happens in most of the cases. Please be very sure of the relationship. As if you are not sure you should give more time to the same.
Please also make sure you are over the age of 21 years.