Should I Be Getting Married?

My boyfriend and I have been together since we were 13 years old. I am now 18, and he is 19. Currently, he is a soldier serving in Afghanistan and will be home on leave in October of this year. We are very young but we have had plans to get married for a little over a year now. When I discuss this with my parents the only thing they seem to believe is that I am getting involved in a contract marriage simply because of the money. However, this is not the case. We want to be able to live together in our own home off base when he returns to the States, and this is possible only if we are married. We are positively in love and plan on having an actual wedding back in our home state when he is discharged. What is so wrong about this plan??