Advice please!?

So, I have a boyfriend, I'm 16 and a white American, he's 25 from China and has only been in America for 2 years and can't speak and understand English too great, and respects that I'm only 16, and waiting to marry me when I turn 19, because that's when I graduate HS. I love him so much and I want to spend the rest of my life with him, but I admit that I am afraid of marriage, I feel like I won't be a good wife! He also wants to have kids, I think 2, but I am scared to death of becoming a parent because it's too much responsibility, I don't even feel responsible now as it is, and everyday I wreck my brain over this! I want to have kids with him when we marry because they will be cute Chinese American kids, and I will love them to death because of it, but I just don't feel suited to be a parent! Any opinions or advice please? Also, we are both virgins, so don't worry!