when should i replace my mirena?

i’m a 23y/o and i got my mirena inserted in october of 2021. i use it for birth control, but also as a way to make sure my cycle is more regular and lighter.

i haven’t been to my obgyn in about 3 years (i was in grad school and quite literally had no extra time for appointments) and i cannot remember after how many years she said to replace it. for some reason i have 5 years in my head but after doing some research it just says 5-8 which is vague. really stupid question but how do i know when it’s time to replace it?