I just got an IUD I have a question

I'm 15 and have been sexually active for about 7 months with my boyfriend of 9 months (I've always used protection) and I forgot to ask my doctor a question after I got it fitted. I'm aware the likely hood is low of it falling out but still possible so I was wondering, would I be certain to know it's come out or is it possible to expelle it without knowing (peeing,period ect). I know it's a silly question o just over think things. thanks for your time Is love an answer.