Am i the only one who had this?

So when i was younger and when i got my period somehow it was always irregular i couldn't keep right track of it because it always started and ended on an different date . Later it stayed on the end of everymonth , but after some months it started to swift again causing my period to start at the beginning of the next month , that changed again to somewhere like the 20st everymonth and now it is   The 18 everymonth -.- . Like seriously? Am i the only one where it swifts like that?😅