IUD STRINGS ARE GONE

Tilley
I will have had it for a year on April 30th. I can't feel my strings. I can feel the opening to my cervix, and all of my cervix, but not my strings. I've always been able to feel them. Do I go to the ER or wait until tomorrow and call my doctor? I have an appointment but it isn't until April 16th... I'm freaking out!