PREGNANCY ANNOUNCEMENT HLP

SO.. I need help on how to announce my new pregnancy to my parents. some back story: I'm 19, my husband is 21, we have an 18 month old. my parents were obviously devastated the first time I was pregnant, I was in high school, not married, etc. Well I graduated, got married, we have our own place, my husband is in college and I got a certificate. NOW.. I know my mom will be upset again (but hopefully not nearly as much).. I'm an adult with a job and a husband and son. It'll be okay. I want to surprise them but I don't know how or when. I was thinking about after I get an ultrasound but that will probably be a month away and I can't wait that long. what do you think?? I'm so nervous they will yell at me.