Mom keeps nagging me about marriage rant!

Okay well for starters I'm 22, SO is 23 and we are pregnant with our first child. 14 weeks well my mom is so hellbent on we need to be married or at least engaged. It's really getting on my nerves. I'm currently a college student and the plan even before I got pregnant was I'm going to be finished with my degree before we get married. Well she keeps saying stuff like it's not what I want its what my SO wants and she doesn't like that. Even though I've told her this is how its going to be. I feel like the only reason she wants me to be married or engaged is to make herself look better to people. My sister got pregnant at 17 my niece is 3 now. She's still with the dad and they just now started talking about rings. Well when I told her I was pregnant she sad she was going to have the shit daughters that both got pregnant and not married. Like get over it ! It's not the 1950s anymore you don't have to be married! Especially not right now yes we are having a child and have been dating for 4 years but eventually marriage is going to happen just not right now. I just get so annoyed that she won't stop bringing it up. Rant over.. Sorry if that was really long!