Advice?

So I am pregnant and due in december, I have told a few friends but not any of mine of my boyfriend's family. My boyfriend doesn't want to tell anyone in our family because he is scared they will freak out on him but I can't keep not going to see my family because how nauseous I have been. I also am scared to tell my family but I know my mom will support me no matter what. I am not sure how to announce it or if I even should for a while to prevent my boyfriend from getting mad at me. I need a little advice on what to do. My 21st birthday is coming up and I don't want my friends to go and buy me a bunch of alcohol that I want drink either, but knowing those friends they would post the pregnancy everywhere if I told them and I don't want them figuring out they are going to gain a new family member through social media.

When or how should I start telling people?