Plan B/ Telling my Mom

Last week during my fertile stage I had sex with my boyfriend. We used a condom but it broke and he pulled out as soon as he felt it. We stopped after that and talked. We agreed that I would take a plan b just to be safe but he was certain nothing went in me but you know 🤷🏻‍♀️. That night we hurried to get a plan b and I took it right away. I haven’t had my period.. my calendar says I should be starting next week .. I feel like I just need reassurance that I did everything right.

On the other hand .. how do I tell my mother I’m sexually active??! Me and my mom never really talk about these things but I feel like I should be on birth control which is something I don’t even know if my mother would support. What do I do? I’m 18 years old.

Thanks!