How to tell your mom/sister you got your period!!!?? (any moms? or girls?)?

So i have had my period fro 2 month now i just turned 13 and i got it for the 1st time in decemberand im on it now. Both my sisters have their periods. And there names are kelsey and sally. (sally-9th grade and kelsey-11th grade) and i STILLL did tell my mom or sisters. So i have pads and tampons under my sink cause my sisters have theirs and we all have pretty much the same cycles. My sisters and I are super close and they always tell my mom and me and each other when they're on their periods. I really want/need to tell my mom and/or sisters!!! Like to explain our closeness we like share the same bra's and we aren't all the same size(kelsey-36C, sally-34C,me-40B/32C) so we are very very close. And i really need help so please tel me how to tell my sisters/mom. Also how old where you when you got your period and how did you tell your mom or sisters you got it? And when did you get it like at schoool? etc... And if you want to know why im asking its because maybe i can resemble to you and im just wondering. thanks!!!