Girls lone PLEASE?

yestoday I found a big brown stain in my underpants, and (I thought it be poo) so I changed and ignored it, but when I wipe I saw dark rusty red! so I wore a wipe that night surrounded by case and I found alittle red on it, and when I wipe there be alot of red, so can I be sure thats my first period? yeah its your first time! i didnt have any cramps any.it was newly a total surprise when i woke up! couldnt even feel it
If it end 3-5 days, yes ma'am welcome to womanhood