Military relationships & marriage

My SO has been in the Marines for over 2 years. He is 20 and I am turning 20 in a couple months. We have been together for well over a year. Well the other day we were talking with one of his higher ups and when he asked if we were married and we replied back with no, he was beyond surprised stating "wow not married or pregnant and you've been together over a year, that's surprising". I don't know why but it really made me uncomfortable like we were supposed to have done all of those by now. I don't know I guess just looking for some feedback on if it is normal to not be married/pregnant yet. And why is there such a stigma about Marines getting married/ getting pregnant so fast?