iud string feels shorter

i got the mirena about a month ago and i kept checking the string to make sure everything was where it was supposed to be and each time i felt up there i could feel the string coming out about an inch or two from my cervix. i stopped spotting and i had sex and i just went to check again and the string was so short that the tip of it was barely sticking out of my cervix and it was very hard to find. is this normal or did having sex move my iud out of place? my next check up at the gyn is in three weeks but i’m really freaking out 😭