Gosh my daughter is going to be 16 in a few months and there is no way in Hell I'd let her shack it up with a married 25 year old and his pregnant wife. This is my mother's instinct speaking here.
Go to college, get an education, make yourself financially sufficient and yeah, boys your age may be immature but there's a reason for that. You learn how to evolve yourself in those relationships.
With being so young, are you sure it's "true love" and not some infatuation? I thought I would die when my boyfriend broke up with me my senior year (he was 5 years older than me) and within a few years, I realized it was "first love" "puppy love" and that there were many more opportunities of meeting the "one" but first, first I had to love myself before I could really fall in love with any one else. My next big love was my husband and that was 4 years later and after many flings with many boys.
I hope you decide to not go through with this. You have so much to experience and getting tied down with a couple and a baby is not where I would want to be if I could be 18 all over again.