Talking to mom

Im 15, and Ive finally made the decision to tell my mom that I'm sexually active. (Partially because my period is late, but I haven't had sex this month and I've been really stressed so it might be late due to stress) I'm going to have my boyfriend there with me, and maybe my best friend, and I'm honestly really nervous to tell her, but I know it will be a good thing , no matter how she reacts, and she'll be glad that I was honest with her, and then our bond can grow stronger