Mom doesn’t want me to tell my family about my engagement

I’m 19 and I just got engaged. My fiancé and I have been together for 2 years (will be 2 years on Christmas) and we got engaged on Sunday. I finally told my mom we were engaged today after putting it off all week from being nervous and also not seeing her because she was working and so was I. She wasn’t happy. She said I was too young, even though she got married directly out of high school. She also doesn’t want us to announce it to the rest my family (aunt, uncle, cousins, grandma, and grandpa) on Sunday at our family dinner. She thinks we should keep it on the DL for a while but I don’t think we should have to. Not everyone is going to like it and that’s fine. It’s not everyone’s engagement. We’re happy. We have a plan. We’re about to get a new apartment and I graduate from school in July. We plan on moving to Florida when I graduate too because they have good jobs for both of us down there. I know 19 is a young age to get engaged, but we have a plan, and we’re sticking to it. What should I do?