Super Nervous

We found out a little over a week ago that we are expecting our first child and I'm only 5w5d. I want to tell my parents that I'm pregnant next weekend when we have our family weekend together but I'm so scared that they'll freak out and be disappointed in me and that they'll not be supportive of me and my decision to have a baby at my age. I'm turning 21 next month and my mom had my brother when she was 16 and me when she was 20 and she was a single mother who had a tough time raising us so she's always etched it in our brains to wait until at least 25 before getting pregnant. However, I've always been the odd one in my family, I've never quite fit in and I've always been one to do my own thing and this is certainly no exception. I'm genuinely in love with my fiance and we plan on raising this baby together so its not like I got knocked up by someone I don't even like. I don't know if I'm freaking out over nothing or if I have a reason to be super stressed about telling them. I know if I don't tell them it'll be much worse and I want to include them in our baby's life but I'm worried they'll be disappointed and non-supportive. Does anyone have any advice on how I can calm myself down about this? Please comment!