MARRYING YOUNG

Okay I'm 18 turning 19 and me and my boyfriend been together for 2 years and best friends for 2 so really 4. I can honestly say we never got in a fight, I never had to worry about him cheating or being rude to me. He has always been there for me even in my roughest times. He doesn't have to worry about me cheating on him either. We honestly have the best relationship ever because he is my best friend and I can tell him everything (literally.) where I'm going with this is, I want to marry soon. My family wants me to marry if we are being sexually active. His family doesn't want us to marry yet. We are secretly planning on getting our marriage certificates next fall, closer to February... what I'm asking is, should we go along with it and have our family treat us like sh** or should we finally ignore what they say???