"Mom I'm having sex."

My mom told me that if I ever became sexually active I should tell her. Well that time has come. I've been dating my boyfriend for almost 2 years. And we both took each other virginitys not too long ago. We have only done it once. I know we might to start do it more but not too much since we're both busy. I almost feel like I should be put on birth control. Also.. I feel kinda guilty from hiding it from my mom. (Then again it's my business ) should I tell her!? I feel like she would flip because she was a teen mom and doesn't want me to be or maybe understand. I have one family member who knows and keeps it a secret. She might be able to get me birth control but I still feel guilty if I got it behind my moms back... Help?