My mom doesn't know I had sex!

So I never told either of my parents when I started having sex! I just don't feel comfortable having that conversation with them as they are really old fashioned and conservative. I feel like they would be really disappointed in me if they knew I was sexually active. I love my parents and I feel guilty for not telling them about my sex life but at the same time I just don't feel like it's appropriate to share that with them. What are your ladies' opinions on this topic? Is it bad that I don't share this with my parents?