I understand op! Your feelings are valid.
Here are some ideas
Reassure her that she is taking a step on a long journey to womanhood, but she is still a girl and changes happen slowly over time.
Bond with her, take some time together to share feelings. Stories of your first period.
Get some comfort items such as fluffy socks, nice pj's, snacks.
Let her know that periods are a great way to relax and take it easy for a few days.
Women are cyclical in nature and we can listen to our bodies and go with the flow of how we are feeling.
Women are amazing! Our blood makes us stronger and wiser. Our wombs are the centre of creation - of ideas, of passion, of excitement and of growth, not just for making babies!
Our periods remind us that there are new beginnings possible always. That nothing stays the same and change is always possible.
That without periods, there is no new life and that is a miracle 🙏
But most of all, there are no expectations. This is a step on a long journey to adulthood and you will be with her every step of the way