I wouldn’t ‘die’ if my Mum knew my cycle. I think it’s nice and when my Mum tracked mine (back on the kitchen calendar, cringe) she knew when to buy me ice cream and offer a hug and when to leave me be. You sound like a lovely, thoughtful Mum!
My mum tracked mine, just by putting my initials in her family calendar, and for my sister too. Let her know when to top up supplies of sanitary items and chocolate. I still keep track now, GP was impressed when I could show her 6 years of cycles. We all have PCOS so it's a good habit to have and I will do the same for my daughters. No need to make a song and dance about it.
My dd wouldn't 'die' if I know when she's having a period, in fact she usually comes and tells me, in between bouts of hormonal crying and stuffing her face with chocolate. And when she starts hers it reminds me mine is due a couple of days later!