Is 18 to young to know you are in love? Should I ask her?

I am joining the U.S Navy ad leaving in October this year. I am pursuing a degree in business administration while I am in the navy and my girlfriend of 1 year is staying in our hometown and going to college to be a social worker. Her family like mine has no savings for her for college. I am very deeply in love with this girl and can see myself with her the rest of my life. Her family is very supportive of us as a couple. I am wondering is I should ask her to marry me before I leave nd sign the marriage papers now and so she could get a lot of military aid towards college. Or should I wait another year or two and then as long as we can manage a relationship with me being an active duty sailor marry? Also my other reason for wanting to marry her before I leave would be if I died my benefits would go to her so that even if I couldn't take care of her she would have a lot of help to live a happy successful life. I really am unsure what to do thanks for the help.